Western Region - Drinking Water Inspectorate

Drinking water 2010
Drinking water
2010
Public water supplies in the
Western region of England
July 2011
A report by the Chief Inspector of Drinking Water
Public water supplies in the Western region of England
Drinking
Water Inspectorate
| Ergon House,
Horseferry
Road | |London
| SW1P
2AL
| Tel:
030
0068 6400
Drinking
Water Inspectorate
| 55, Whitehall
| London
SW1A 2EY
| Tel:
020
7270
3370
www.dwi.gov.uk
http://www.dwi.gov.uk
PB13481
Western region
Drinking water 2010
Western region of England
1
Drinking water 2010
P ub l is he d b y
Dri nk i ng W ater Ins p ec tor at e
Ar ea 4a
Er go n H ous e
Hors ef err y R o ad
Lo n do n
SW 1P 2 AL
T el: 0 3 0 0 06 8 6 4 00
W ebs ite : ww w. d wi . go v .uk
© Cr o wn Co p yr i gh t 2 0 11
IS B N : 97 8- 1- 9 0 58 5 2 - 5 5- 0
Co p yr i gh t i n th e t yp o g r ap h ic a l ar r an g em ent an d d es ig n res ts wi t h t he Cr o wn .
T his p ub l ic at i on ( ex c lu d in g t he lo g o) m a y b e rep ro d uc e d f r ee of c h a rge in an y
f orm at or m ed i um pr o v i de d t ha t i t is r e pr od uc ed ac c ur at e l y a n d no t us e d i n a
m is le a di n g c o nt ex t . T h e m at er ia l m us t b e ac k no wl e d ge d as Cr o wn c op yr i g ht wi th
th e t it l e a nd s o ur c e of th e p ub l ic at i on s pec if i ed .
2
Western region
Contents
Introduction
4
W ater supply arrang ements
8
Drinking water qualit y test ing
10
Drinking water qualit y results
11
Drinking water qualit y events
32
Technical audit activit y
34
Public conf idence in drinking water quality
36
Planned drinking wat er qualit y improvements
40
Annex 1:
Further sources of inf ormation
45
Annex 2:
Glossar y and description o f standards
46
Annex 3:
Drinking water qualit y events in the region
59
Annex 4:
Planned drinking wat er qualit y i mprovement s
68
Annex 5:
Compet ition in the water industr y
71
Annex 6:
W ater company indices
73
Drinking Water 2010 is the annua l report of the Drinking Water Inspectorate and
c o mp r i s e s r e p o r t s c o v e r i n g p u b l i c a n d p r i v a t e w a t e r s u p p l i e s .
Public supplies – This part describes drinking water quality in the Western region. The
I n s p e c t o r a t e a l s o p u b l i s h e s a s e r i e s o f c o mp a n i o n r e p o r t s o n p u b l i c s u p p l i e s f o r o t h e r
r e g i o n s o f E n g l a n d ( C e n t r a l , E a s t e r n , N o r t h e r n , S o u t h e r n a n d T h a me s r e g i o n s ) a n d a
separate report for Wales.
P r i v a t e s u p p l i e s – A s u m ma r y o f i n f o r ma t i o n o n p r i v a t e w a t e r s u p p l i e s i s r e p o r t e d f o r
England and Wales.
A l l p a r t s a r e a v a i l a b l e o n t h e I n s p e c t o r a t e ’s w e b s i t e w w w . d w i . g o v . u k .
3
Drinking water 2010
Introduction to the report for the Western region
Drinking water 2010 is published as a ser ies of nine reports, seven of
which cover public water supplies and t wo descr ibe pr ivat e water supplies
in England and W ales. Each report presents inf ormation about drinking
water qualit y in a f orm that meets the needs of those who have an interest
in the qualit y and saf e management of drinking water supplies f rom the
consumer ’s per spect ive, namely the local authorit ies and the r egional
committees of the Consumer Council f or W ater.
This report describes the key f acts about the qualit y of public drinking
water supplies in the W estern region, which is ser ved by seven water
companies (Bournemouth and W est Hampsh ire W ater, Bristol W ater,
Cholderton and District W ater, South W est W ater, W essex W ater and t wo
inset appoint ees : Veolia W ater Projects Ltd who manage water supply
arrangements at Tidworth and SSE W ater who ser ve O ld Sarum, Salisbur y )
delivering wat er supplies to over f our and a half million consumers .
4
Western region
The results of testing in 2010 demonstrated that the over all qualit y of
drinking water in the W estern region was good. The f igure f or compliance
with dr inking water standards at consumers’ taps was 99. 97% , the same as
that reported in 2009 and above the industry over all average . This f igure is
made up of the results of all the tests f or 39 parameters wit h European or
national standards.
W hen the W estern region is judged by the Inspector ate’s f our indices of
water qualit y perf ormance, which look in turn at water treatment
(comprising process control and disinf ection) , ser vice reser voir integrit y
and net work maintenance, the main change in 2010 was impr oved f igures
f or disinf ection (99.95%) and reser voir int egrity (99. 97%). Compared to
last year, process control declined to 99. 96% predom inantly due to
trihalomethane f ailur es reported by Br istol W ater. The network
maintenance f igure was unchanged in 2010 at 99.94%. Two indices,
net work maintenance and r eser voir integ rit y, were above the industr y
average. The process control f igure, though improved, was the lowest out
of all the regions and the disinf ection f igure was the joint lowest in
England. Individual water company f igures are reported in Annex 6.
Across the region there was no change in the number of events aff ecting
water qualit y: 42 compared to 41 in 2009. Approximately one -third (17)
were of a type that necessitated a detailed investigation by an inspector.
This is similar to the proportion of events r equiring c loser scr utiny in 2009.
One serious event in 2010 did necessitat e deployment of a considerable
amount of the Inspectorate’s resource. The cause of the event was the
connection of a new propert y to a sewer r ather than to a water main.
It was f ort unate that this was detected f airly quickly. The misconnect ion of
a propert y to a sewer is an error with potentially ver y serious
consequences f or public health and the I nspector ate is ver y concerned
that this is the second year in a row when such an event has occurred. The
event is descr ibed in more detail in the Drinking water quality events
section. In terms of the nature of the events reported on this year, there
has been no marked change f rom the general pattern f or recent years.
Detailed f indings rega rding all the signif icant events in 2010 can be f ound
in Annex 3. In 2010, risk -based technical audit highlighted analytical
malpract ice at a laboratory operated by Severn Trent Ser vices aff ecting
eight water companies and six regions (see the Technical au dit activity
section f or f urther details).
The long -term trend in public conf idence in dr inking water qualit y
continues to improve in the W estern region. The number of people across
the region expressing concern about the qualit y of their tap water
(appear ance, taste and illness) has continued to f all. By com parison to the
other regions, the W estern region st ill has the highest contact rate (3.9 per
1,000 populat ion), however , there is a longer term downwar d trend in
5
Drinking water 2010
consumers reporting black, brown or oran ge water with part icular ly good
improvement this year in the ar ea operat ed by South W est Water.
However, the previous progress in reducing white wat er cont acts has
slowed and ther e remains no clear trend of improvement in r elat ion to
objectionable chlor ino us taste or odour contacts , although these wer e
f ewer in number in 2010 compared to 2009. Disappointingly , the number of
consumers who were suff icient ly dissat isf ied to take the matter up direct ly
with the Inspectorate doubled in 2010 (six compared to thre e in 2009).
This year sees the 20 -year anniversar y of the implementat ion of the
European Drinking W ater Directive and this report contains a summary of
how the approach to regulating f or saf e , clean drinking water for all has
developed over t wo decades. A n over view of how this translates into
action in the region is contained in the Planned drinking water
improvements sect ion. Additionally, Annex 4 contains inf ormation about
the schemes of work deliver ed by companies in 2010 and those planned
f or deliver y over the next f our years.
In reviewing drinking water qualit y in 2010, the Inspector ate considers that
two topics are worthy of highlighting to the industr y. The f irst concerns the
number of events and f ailures of drinking water standards which have been
due to cross-connect ions or misconnect ions bet ween the dom estic water
supply and other sources , f or example rainwater, pr ivate water supplies
and in one instance in the W estern region, a sewer. These def ects
generally occur at points close to the consumer , theref ore the risk to
public health is high. Companies need to give high pr ior it y in t heir water
saf ety plans to control measures to addr ess these r isks , such as accur ate
records of net work assets, the competency of those who work on the
net work and more appropriate targeting and priorit isat ion of f ittings
inspect ions. Although companies have recently been ident if ying and taking
enf orcement action in relat ion to cr oss -connect ions bet ween the public
water supply and eit her domest ic rainwater har vest ing syst ems or private
water supplies, the Inspector ate has f ound it necessar y to remind a
number of companies that f ittings inspect ions need to be carr ied out when
investigating f ailures of drinking water st andards, particularly in relation to
the f ollowing param eters: taste, odour, lead, copper, nickel, E.coli and
Enterococci. As a result of changes to the regulations to br ing them into
line with the EU Drinking W ater Directive, it is mandator y to consider
carrying out f ittings inspect ions as part of invest igatio ns into failures
arising in public buildings and also when requested by a local authorit y in
relat ion to r isk assessments of private water supplies. Companies need to
make sure that these changes have been ref lected in their policies and
practices relating to f ittings inspect ions , which should be given a higher
prof ile in relation to water saf ety plan methodolog y and should be taken
into account during regulator y risk assessments.
6
Western region
The second obser vation concer ns bulk supplies. These are situations
where one water company relies on anot her f or a source of either raw or
treated wat er. In relation to a number of events or f ailures of drinking
water standards , it is evident that arrang ements in relat ion to these bulk
supplies are less than adequate. In part icula r, companies who import bulk
supplies are rem inded that they are under a dut y to carr y out a f ull risk
assessment and it would be advisable f or there to be f ormal arrangements
to ensure that such supplies are both wholesome and f it f or human
consumpt ion be f ore supply to their own customers. The regulatory r isk
assessment (and f ormal agreement) must include arrangements f or
alternate supplies of water in the event of either a qualit y or quantit y
event. There is a need f or jointly agreed risk assessments , ensuring f ull
awareness of the control measures with clear lines of accountabilit y and
communication under both normal and abnormal operat ing sit uations.
7
Drinking water 2010
Water supply arrangements
Seven water companies supply dr inking water in the W estern region:
Bournemout h and W est Hampshire W ater (BW H), Bristol W ater (BRL),
Cholderton and District W ater (CHO), South W est W ater (SWT) , W essex
W ater (W SX) and two inset appointments; Veolia W ater Projects Ltd
(VW P), suppl ies consumers in the Tidworth area, and SSE W ater (SSE)
ser ves Old Sarum, Salisbur y.
Figure 1: Map illust rating sources of drinking w ater by zone across
the region
Much of the water in the region is der ived f rom surf ace water (67%)
abstracted f rom river s such as the Severn, the Hampshire Avon, Dart, Exe,
Fowey, Tamar and the Dorset Stour. There is a major transf er of water into
the region via the r iver Severn f rom reservoirs in W ales which provide half
of the daily supply to the Bristol W ater area. Addit ionally, the upland ar eas
of Bodmin Moor, Dar tmoor, Exmo or and t he Mendips ar e important
catchments f or water resources in the reg ion. Surf ace water is drawn f rom
many reser voirs, including Chew Valley Lake, Clat worthy, Collif ord,
Roadf ord and W imbleball. Groundwater provides a valuable resource
(27%) in the region, with many boreholes drawing water f rom the chalk
aquif er of the W essex basin. The Permian and Triassic sandstone aquif er
in the Otter Valley is also an important groundwater source f or East
Devon. Cholderton and District W ater relies exclusively on t he chalk
8
Western region
aquif er of the W essex basin. Across the region, a small pr oportion of water
supplies (6%) can be drawn f rom either surf ace or groundwat er sources.
Summar y f acts about the drinking water supply inf rastructure of the region
are set out in Table 2 along with outline geographical and demographic
inf ormation.
Table 2: Key fact s about the West ern region suppl y arrangements
Key facts
Population supplied
Water supplied (l/day)
Number of local authorities
(with a further 6 partially
covering the region)
4,560,999
1,249 million
27
Abstraction points
Treatment works
Service reservoirs
Water supply zones
Length of mains pipe (km)
Area of supply
Cornwall, Devon, Dorset, Gloucestershire (part),
Hampshire (part), Somerset and Wiltshire (part)
9
Water composition
Surface sources
Groundwater sources
Mixed sources
349
153
810
188
35,587
67%
27%
6%
Drinking water 2010
Drinking water quality testing
Throughout 2010, water companies sampled drinking water across the
region to test f or compliance with the st andards in the drink ing water
regulations. Approximately one-thir d of the tests wer e carried out on
drinking water dr awn from consumers’ taps selected at random .
For monitor ing purposes, company water supply areas are divided into
zones based on populat ion (maximum 100,000). Generally, zones are
sampled at consumer taps with the number of required tests being greatest
in zones with larger populat ions. Other sample locations are water
treatment works and treated wat er (ser vice) reser voirs. Collectively , the
seven water companies carr ied out a total of 592,162 tests during 2010.
Only 117 of these tests f ailed to meet the standar ds set down in the
regulations.
Table 3: Number of tests carried out by companies in the region
Pl a ce of s a mpl ing
Comp an y
W at e r
t r eat me nt
w ork s
S erv ic e
re s e rv oi rs
Con sum e rs ’
tap s
(z one s)
Numb e r of
E sti mat e
tes ts p er
com pa n y
of
popul at ion
B our n em out h
an d W es t
Ham ps h ir e
W ater
13 , 69 6
( 8)
6, 1 74
( 20 )
16 , 29 1
(10 )
36 , 16 1
42 6 ,0 0 0
Br is t o l W ater
27 , 30 7
( 17 )
50 , 32 0
( 16 5)
41 , 94 7
(52 )
11 9 ,5 7 4
1, 1 36 ,0 0 0
Ch o ld er to n
an d D is tr ic t
W ater
37 7
( 1)
31 2
( 1)
32 8
(1)
1, 0 17
3, 0 00
S ou th W es t
W ater
52 , 93 7
( 33 )
85 , 52 7
( 28 4)
66 , 02 3
(32 )
20 4 ,4 8 7
1, 6 82 ,0 0 0
S S E W ater
0
( 0)
0
( 0)
22 8
(1)
22 8
99 9
1, 2 64
( 2)
1, 5 60
( 6)
61 2
(1)
3, 4 36
8, 0 00
W es s ex
W ater
77 , 07 3
( 83 )
92 , 63 5
( 29 8)
57 , 55 1
(91 )
22 7 ,2 5 9
1, 3 05 ,0 0 0
Reg ion
ov er a ll
17 2 ,6 5 4
( 14 4)
23 6 ,5 2 8
( 77 4)
18 2 ,9 8 0
(18 8)
59 2 ,1 6 2
4, 5 60 ,9 9 9
V eo l i a W ater
Pr oj ec ts Lt d
N u m b e r s i n b r a c k e t s r e f l e c t t h e n u m b e r o f wo r k s , r e s e r v o i r s o r z o n e s o p e r a t e d b y t h a t c o m p a n y
in the region in 2010. Some companies are permitted to carry out some tests on samples taken
from supply points rather than from consumers’ taps.
10
Western region
The regulations require companies to test f or specif ied param eters at
prescribed f requencies. Most of the testing is f or parameters with
Europ ean or n ational standards, however, water companies ar e also
required by the regulations to test f or other parameters , such as
ammonium, sulphate and colony counts.
A summar y of the results of testing by companies f or each parameter can
be f ound on the DW I website ( www.dwi.g ov. uk ) and on the CD
accompanying this r eport.
Drinking water quality results
The key water qualit y results f or the W estern region are pr esented in t wo
tables, one showing the results f or microbiological parameter s (Table 4),
the other dealing wit h chemical and physical parameters ( Table 6).
The microbiological qualit y of water is discussed f irst. Companies report
all the results of the tests on a monthly basis to the Inspect orate. Also ,
tables in Annex 6 describe the perf ormance of ea ch company supplying in
the region.
Microbiological quality
To protect public health, micr obiological standards have to be met at each
individual treatment works and ser vice reser voir. The results conf irm the
overall m icrobiological saf ety of drinking wat er supplies in the region.
The signif icance of the individual test results f or each microbiological
parameter at each location varies and a single positive result cannot be
interpr eted without other inf ormation. All companies ar e expected to f ollow
best pract ice as set out in The Micr obiology of Dr inking Water published by
the Standing Committee of Analysts (SCA) which can be f ound by visiting
the Environment Agency’s websit e ( www. environment -agency. gov.uk ).
11
Drinking water 2010
Table 4: Microbi ological tests
The number of test s performed and the number of tests not meeting
the standard
P ar am et e r
Cu rr ent
st a nd ar d
T otal
numb e r
of t est s
Numb e r of
tes ts not
me eti ng
the
sta nd ar d
Ad di tio na l
info rm at ion
W ate r l e av ing w at e r t re at me nt w or k s
E.c o l i
0/ 1 00m l
23 , 17 0
3
Co l if orm b ac t er i a
0/ 1 00m l
23 , 16 8
18
Cl os tri d i um
per fr i ng e ns
0/ 1 00m l
5, 3 26
5
1NT U
23 , 11 4
6
39 , 49 3
3
39 , 49 2
17
T urb id i t y
1
W ate r l e av ing s e rv i c e r es e rv oi r s
E.c o l i
0/ 1 00m l
Co l if orm b ac t er i a
0/ 1 00m l i n
95 % of t es ts
at e ac h
r es e r vo ir
BW H (2), SW T (1)
BR L (2) , BW H (5),
SW T (5), W SX (6)
BW H (1), SW T (3),
W SX (1)
CHO (1 ), SW T (1),
W SX (4)
SW T (3)
BR L (1) , SW T (10),
W SX (6)
A l l 77 4 res er v o irs
i n th e r e g io n m et
th e 9 5%
c om pl i anc e r u l e
W ate r s a mpl ed at co nsu me r s’ t a ps
E.c o l i
0/ 1 00m l
12 , 54 5
4
E nt er oc oc c i
0/ 1 00m l
1, 4 84
1
1
BR L (1) , BW H (2),
W SX (1)
W SX (1)
Tu r b i d i t y i s a c r i t i c a l c o n t r o l p a r a m e t e r f o r w a t e r t r e a t m e n t a n d d i s i n f e c t i o n .
E.coli at w orks
In 2010, a total of 23,170 tests at works were carr ied out by all the
companies across the region and E.coli was det ected in just three samples
(2 BW H, 1 SW T) .
On detecting E.coli, companies ar e required to act promptly t o protect
public health. Their immediate response when f inding E.coli at a works is
to sample again , and more widely, to conf irm that water being received by
consumers is saf e . In 2010, these addit ional tests gave satisf actory results
in all cases and there were no subsequent E.coli f ailures.
Bournemouth and W est Hampshire W ater detected E.coli in a sample taken
f rom Knapp Mill works (near Bournemout h ) in Febr uar y. The works was
operat ing normally at the time and the company concluded that a new
sample tap f itted the previous day was unsuitable; the tap was replaced
af ter cutting it open revealed poor cast ing . Although there have been no
f urther E.coli detect i ons; Clostr idium perf ringens was detected in a sample
12
Western region
in March and this will be taken into account during the Inspect orate’s r isk based programme of technical audit.
E coli was reported by Bour nemouth and W est Hampshire W ater from a
sample taken at Alderne y works (near Bournemouth) in June ( see Annex
3). In response the company concluded t hat f aults wit h the sample
f acilit ies were contributor y f actors but the Inspector ate was not satisf ied
with the unclear explanation provided by the company. Not ing that , since
2008, ther e had been f our separate occasions where colif orm bacteria,
including E. coli, had been detected in samples collected f rom this works
the Inspector ate made f urther enquiries of the company wher eupon details
were provided of inspections of th e treated water reser voir which showed
ingress of f iltered water which had not been disinf ected. At this site the
slow sand f ilters are located direct ly above the treated water reser voirs
and vents passing upwards through the filt er had been sealed , in 2008, in
a manner that was not robust. As a consequence , a proportion of f iltered
water was routinely bypassing the disinf ection process. The Inspectorat e
was ver y cr itical of the company f or f ailing to recognise , in its risk
assessment , that the locat ion of f ilters above a contact tank poses an
obvious high risk requir ing caref ul management and enhanced monitor ing
at all times. The Inspectorate was also very cr itical of the company f or
f ailing to make the link between a known integrit y risk at the works and
sample results , and f or a generally tardy response to a potent ially serious
problem. In particular, the company overlooked entir ely that failures were
occurring at consum er taps in the downst ream zone (see sect ion on E.coli
and Enterococci at consumers’ tap s). The company has put in place a
more eff ective engineering solut ion and updated its r isk assessment to
ref lect the additional risk mitigation measures now in place .
In August, South W est W ater detected E.coli in a sample taken f rom
Crownhill works, near Plymouth (see Annex 3). An external inspection at
the site did not reveal anyt hing untoward , however, the contact tank had
not been inspected internally since 1998. Af ter some enabling works, the
contact tank was isolated and inter nally inspected in Apr il 2011 which
revealed several points of potential ingress. All the remedial works has
been completed and the contact tank has been retur ned to s er vice.
Cleaning and inspect ion of the t wo large treated water storage tanks i s
near ing complet ion.
13
Drinking water 2010
Table 5: Detection of E.coli and Enterococci at treatment w orks,
service reservoirs and consumers’ taps
Comp an y
E. co li i n
w at er
le av in g
t r eat me nt
w ork s
E. co li i n
w ater
le av in g
se rv i c e
re s e rv oi rs
E. co li a t
con su me r s’
tap s
Ent e ro co cc i
at
con su me r s’
tap s
B our n em out h a n d
W es t Ham ps h ir e
W ater
2 – 1 ,5 8 2
0 – 1 ,0 3 0
2 – 1 ,1 7 5
0 – 91
Br is t o l W ater
0 – 3 ,7 0 8
0 – 8 ,3 8 7
1 – 3 ,0 7 1
0 – 3 88
0 – 53
0 – 52
0 – 12
0 – 4
1 – 7 ,0 1 6
3 – 1 4, 2 55
0 – 4 ,4 6 5
0 – 3 79
0 – 0
0 – 0
0 – 12
0 – 4
0 – 2 08
0 – 3 12
0 – 24
0 – 8
W es s ex W ater
0 – 1 0, 6 03
0 – 1 5, 4 57
1 – 3 ,7 8 6
1 – 6 10
Reg ion ov er al l
3 – 2 3, 1 70
3 – 3 9, 4 93
4 – 1 2, 5 45
1 – 1 ,4 8 4
Ch o ld er to n a n d
Dis tr ic t W ater
S ou th W es t W ater
S S E W ater
V eo l i a W ater
Pr oj ec ts Lt d
Coliform bacteria at w orks
Testing f or colif orm bacteria gives reassuranc e that water entering the
supply was treated adequately t o remove bacterial and viral pathogens.
Repeated occurrences of colif orm bacteria in samples f rom the same
works in one year ar e thus of concern and require act ion to be taken .
In 2010, this sit uati on occurred at t hree sites: Alder ney works (BW H) and
Rodbourne works and Briantspuddle No1 works (W SX) .
The three f ailures at Alderney works (BW H) were due to a ser ious design
f ault (see the E.coli at works section).
Following the detect ion of colif orms a t Rodbourne works (near
Malmesbur y, W iltshire ) in March, W essex W ater identif ied leakage f rom
the contact tank, issues with chlor ine control and f low, and t he sample line
tapping was not in accordance with company policy. The sam ple point was
replaced in May and the leakage f rom the contact tank investigated and
f ound to be due to splashing f rom the inlet pipe . Another colif orm f ailure in
August prompted W essex W ater to take part of the contact tank out of
14
Western region
supply to enable minor works to be carried out to improve chlorine control
and mixing. Further investigat ion revealed the need f or more substant ial
work and a major scheme is under way. The company re viewed the raw
water and concluded marginal chlor ination was suf f icient to pr ovide
adequate disinf ection . The Inspectorate has noted that there had been an
earlier colif orm f ailur e in 2009. The Inspectorate expects the company to
update the relevant r egulator y risk assessment and document the actions
taken and planned.
Following two detect ions of colif orm bacteria at Br iantspuddle N o1 works
(near Dorchester ) in November, W essex W ater f ound def iciencies in
relat ion to the sampling f acilities and made a temporar y re-tapping of the
sample point , however, this was also f ound to be unsatisf actory because
the location was subject to f looding with groundwater . The sampling tap
was permanent ly relocated in Februar y 2011 and there have been no
subsequent f ailures. W essex W ater has recognised the need t o improve its
sampling f acilities generally and this is being achieved t hrough a
company- wide project through out 2011.
In Januar y, Br istol W ater detected colif orms in a sample f rom Alderley
works. The usual sampling tap was f rozen due to the severe weather
conditions, so instead, the sample had been collected f rom a n inf requently
used kitchen tap on t he site. In Februar y, the sample tap was lagged and
all subsequent result s have been sat isf actory. This case illust rates why it
is not appropr iate to resort to alternate sampling locations and why
companies should ensure sample f a cilities at all sites are well designed
and proactively maintained.
The Inspectorate has noted that colif orm bacteria were f ound in 18 (2 BRL,
5 BW H, 5 SW T, 6 WSX) samples f rom treatment works in the W estern
region dur ing the year , compared to 17 in 2009, and this inf ormation will
be taken into account during the Inspectorate’s r isk -based programme of
technical audit.
Clostridium perfringens
This organism is a spore-f orming bacterium that is exceptionally resistant
to unf avour able conditions in the water environment , such as extremes of
temperature and pH , and disinf ection pr ocesses such as chlor inat ion and
ultraviolet light. It is a normal component of the intestinal f lora of up to
35% of humans and other warm -blooded animals. These char acterist ics
make it a usef ul indicator of either inter mittent or hist orical f aecal
contamination of a ground water source or surf ace water f iltrat ion plant
perf ormance. The detection of any Clostridium perfr ingens in t he supply
should trigger an inve stigation by the wat er co mpany.
15
Drinking water 2010
In 2010, out of 5,326 samples taken in the region, f ive did not meet the
specif ied value (1 BW H, 3 SW T, 1 W SX) .
In March, Bournemouth and W est Hampshire W ater detected Clostridium
perfringens in a sample f rom Knapp Mill works (see the E.coli at works
section).
South W est W ater f ound not hing untowar d when invest igating reports of
Clostridium perfringens in samples collect ed f rom Stithians works (near
Penr yn) in March, Cr ownhill works (near Derrif ord, Plym outh ) in August ,
and Dousland works (near Yelverton) in December . The Inspectorate
expects companies t o review the relevant regulator y risk assessment in
response to unexplained f ailures.
W essex W ater reported Clostr idium perfringens in a consum er ’s tap
sample f rom the Leckf ord Bridge zone in October . The Inspect orate has
issued guidance to companies regarding the inadvisabilit y of continued
monitor ing of this parameter at consumer s ’ taps, however , this practice
has cont inued in par ts of the W estern region. Accor dingly , the Inspector ate
expects the companies to review and update their regulator y r isk
assessments to take account of detections of Clostridium perf ringens in
consumer tap samples. In Drinking w ater 2009 it was explained that
positive detect ions in surf ace water der ived supplies are indicati ve of
accumulat ions of mains deposits and point towards the need f or
inf ormation on f ailur es to be taken int o account in companies’ Distr ibut ion,
Operation and Maint enance Strategies (DO MS) to pr ior itise flushing work.
Turbidity at w orks
Turbidit y is a m easure of how much light can pass through water and
indicates the condition or ‘cloudiness’ of water. Turbidit y is caused by
particles suspended in the water and is an important cr itical control
measure of the perf ormance of disinf ection. Turbidit y is meas ured at t wo
points in the water supply chain, at treat ment works where a value of
1NTU applies and at consumers ’ taps where the standard of 4NTU applies.
The f ollowing discussion f ocuses on the r esults of samples taken at
treatment works.
In October, Choldert on and District W ater reported a turbidit y f ailure f rom
a sample taken at Cholderton works. The site abstracts water from a chalk
aquif er and raw water qualit y is generally stable . Further sam ples have
proved satisf actor y and the f ailure was considered to be due t o a one -of f
disturbance of chalk deposits.
A f ailure of the turbidit y standard was notif ied by South W est W ater in
relat ion to an event at Prewley works (near Okehampton) in Septembe r.
16
Western region
The Inspectorate was critical of the company f or its slow r esponse to the
coagulat ion problem s at the site (see Annex 3).
In Januar y and again in September , W essex W ater re corded f ailures of the
turbidit y standard in samples f rom Boyne Hollow works (near Shaf tesbur y).
The elevated turbidit y events were linked to pump start up at this
other wise good quality spr ing source. An old cast iron main on site was
identif ied f or replacement . The main was regularly f lushed unt il it was
replaced in November . As part of the improvements at the site the
company re-sited the turbidit y monitor to monitor the treated water .
During the investigat ion of a f ailure of the turbidit y standard in March ,
W essex W ater collected samples f rom all the sample taps at Maundown
works (near W iveliscombe ). The f indings conf irmed a problem with the
location of the routine sampling point and this was changed in July. All
subsequent turbidit y results have been satisf actory.
At W interbourne Abbas works (near Dor chester ), W essex W ater attributed
a turbidit y f ailure in June to entrapped air. A f oot valve on a borehole
pump was thought to be f ailing and whenever the site shut down, air was
sucked into the rising main. On start -up, the entrapped air moved f orwar d
through the works and mobilised sediment . The cause was identif ied as a
hole in the riser and wa s repair ed in December and all f urther turbidit y
results have been satisf actory.
The number of turbidit y f ailur es at works across the region in 2010 was six
(1 CHO, 1 SW T, 4 WSX), a notable improvem ent over previous years
(17 in both 2008 and 2009).
E.coli at service reservoirs
In 2010, across the r egion, a total of 39,493 tests wer e carried out at
ser vice reser voirs by all the companies and E.coli was detect ed on three
occasion s (SWW ).
On detecting E.coli, companies ar e required to act promptly t o prot ect
public health. The im mediate response when f inding E.coli at a ser vice
reser voir is to sample again , and more widely, to conf irm that water being
received by consumers is saf e. In 2010, these addit ional tests all gave
satisf actor y results .
At Port worthy r eser voir (near Plym outh), E.coli and colif orm bacteria were
detected in May and again in June when South W est W ater isolated the
reser voir f or cleaning and inspection (see Annex 3). This revealed some
minor points of ingress around the roof which were sealed. The company
also replaced the sampling f acilit ies. The Inspectorate has noted that both
17
Drinking water 2010
f ailures had occurred during dry periods when surf ace water r un off and
ingress was unlikely .
South W est W ater detected E.coli in a sample f rom Landscore (South
Devon) reser voir in August. The company identif ied the need f or repairs to
the roof to prevent ingress. The reservoir is being kept out of supply unt il
the works are complete.
Coliform bacteria at service reservoirs
Testing f or colif orm bacteria gives reassurance that the quality of water
held at these strateg ic points in the distr ibution system is adequately
maintained. The national standard requir es that at least 95% of no less
than 50 sam ples collected f rom each ser vice reser voir throughout one year
are f ree f rom all colif orm bacteria. In 2010, all 774 ser vice reser voirs
(including wat er towers) in the region met the standard.
In April, South W est W ater reported colif orm bacteria at Bratton Fleming
works (near Barnst able). Following previous f ailur es roof repairs had been
carried out in December 2009. At the sam e time the company had removed
all the soil f rom the reser voir roof to avoid puddling , replaced the sampling
f acilit ies and installed a bend in the reser voir inlet pipe to improve
circulat ion of water. Following the f ailure in Apr il, Sout h W est W ater
started work to install a per imeter drain around the reser voir roof in June .
Inundat ion tests in September were sat isf actor y and the reser voir was
returned to suppl y.
A colif orm f ailure at Brentor reser voir (near Brent Tor ) in May was linked
by Sout h W est W ater to a leak which had occurred as a result of a f rozen
pipe in the severe winter which had weakened the push -f it joint
connectors. The sample line was replaced in July. In November , the
reser voir was taken out of service f or inspection and minor points of
ingress were obser ved around the hatch seals. These wer e repair ed and
the reser voir returned to ser vice in December to enable inspection of the
adjacent cell. Af ter satisf actory completion of the se works there have been
no f urther f ailur es.
A f ailure at Kerris ( Chywoone) reser voir (near Penzance) in May led to
South W est W ater making minor repairs around a redundant hatch cover in
June and schedul ing the reser voir f or an internal inspect ion at a time when
the supply and demand situation perm its.
At Ashbr ittle reser voir (near W ellington, Somerset), W essex W ater
reported colif orm bacteria in a sample taken in July. An investigation
revealed the f low f rom sampling f acilit ies on a pumped supply was diff icult
to control. A related sample point at Spr ing Grove reser voir was also f ound
to be inappr opriate. The sampling f acilities at both sites were replaced in
18
Western region
2011 as part of a company- wide programme of improving sampling
arrangements .
The Inspectorate ha s noted that colif orm bacteria were f ound in
17 samples (1 BRL, 10 SW T, 6 W SX) f rom service reser voirs in the
W estern region during the year and this inf ormation will be taken into
account during the Inspector ate’s risk -based programme of technical audit.
E.coli and Enterococci at consumers’ taps
A total of 12,545 consumers’ taps were tested in 2010 f or E.coli and f our
were posit ive (2 BW H, 1 BRL , 1 W SX ). Like E.coli, the pr esence of
Enterococci is indicative of f aecal contam inat ion and neit her bacteriu m
should be f ound in any sample. In 2010, the companies carried out 1,484
tests f or Enterococci at consumers’ taps and one was positive (W SX).
In all but one case ( Alderney zone) there was no indication, f rom
inf ormation gathered by the water company , of a f aecal cont aminat ion
event af f ecting other properties in this zone.
A f ailure at a consumer’s tap in the Tickenham Portishead and Pill zone in
June was f ound to be due to poor tap hygiene by the invest igation carried
out by Br istol W ater. Colif orm bacte ria and Enterococci wer e found in
investigational samples and swabs f rom the tap . Af ter disinf ection of the
tap satisf actor y results wer e obtained. The consumer was given advice on
tap hygiene.
Bournemouth and W est Hampshire W ater detected E.coli in sample s f rom
Alderney Sout h zone in Apr il and July. The Inspector ate has noted that the
company f ailed to link these f ailures to known problems at Alderney works
(see the E.coli at works section and Annex 3). The company also f ailed to
notif y the local authorit y and the Health Protection Unit (HPA).
W essex W ater reported Enter ococci f rom a consumer ’s tap sample in
Trowbr idge zone in June. The presence of colif orms in pre -disinf ection
samples and in swabs taken from the tap, indicate d the most probable
cause f or t he f ailure was the poor hygienic condition of the tap.
Chemical quality
The drinking water r egulations set out the minimum testing requirements
f or all chem ical and physical param eters. A f ull summar y of the results of
testing by each com pany, including t he r esults f or indicator parameters ,
is provided on the DW I website ( www.dwi.gov.uk ) and on the CD
accompanying this r eport.
19
Drinking water 2010
The f ollowing text and T able 6 set out the results f or those par ameters
where there has been a f ailure to meet a European or national standard
(mandator y qualit y standards) and any ot her parameter of int erest .
In addition, at the request of local author ities, the results of testing f or
f luoride, iron, lead, manganese, nitrate, nitrit e and pesticides are given.
Table 6: Chemical and physical parameters
The number of test s performed and the number of tests not meeting
the standard
Current
standard or
specified
1
concentration
Parameter
Total
number
of tests
Number of
tests not
meeting
the
standard
Additional information
4,138
9
BRL (2), BWH (1), SWT
(3), WSX (3)
4,117
7
BWH (1), SWT (3),
WSX (3)
Aesthetic parameters
– odour
No abnormal
change
– taste
Aluminium
200μg/l
4,452
1
WSX (1)
Benzo(a)pyrene
0.01μg/l
1,437
1
WSX (1)
Fluoride
1.5mg/l
1,199
0
Iron
200μg/l
4,259
8
BRL (5), SWT (1), WSX
(2)
Lead (current standard)
25μg/l
1,461
2
BWH (1), SWT (1)
Lead (future standard)
10μg/l
1,461
9
BRL (5), BWH (1), SWT
(1), WSX (2)
Manganese
50μg/l
4,260
3
SWT (3)
Nitrate
50mg/l
1,815
0
Nitrite
0.5mg/l
1,813
1
Pesticides – total
0.5μg/l
1,165
0
Pesticide – individual
0.1μg/l
39,496
2
2,4-D WSX (1),
Metaldehyde BRL (1)
Trihalomethanes Total
100μg/l
1,486
4
BRL (4)
4NTU
5,040
1
WSX (1)
2
Turbidity (at consumers’
taps)
BWH (1)
Notes:
1
For comparison, 1mg/l is one part in a million, 1μg/l is one part in a thousand million.
2
A further 3,615 tests were done for aldrin, dieldrin, heptachlor, heptachlor epoxide, all of which met the
relevant standard.
20
Western region
Aesthetic parameters
Consumers expect their dr inking water t o be clear and bright in
appearance and f ree from discernible taste or odour. In recog nit ion of this
the regulat ions st ipulate national standar ds f or colour, odour and taste.
Companies are required to investigate the cause of any adver se result.
In 2010, a total of 16 samples f rom consumers’ taps in the reg ion exhibited
a positive taste or odour. All tests in the region met the standard f or
colour.
The posit ive detect ions of taste and odour are summarised below in
relat ion to their nature and cause as determined by the invest igations
carried out by the companies. From this inf ormation it can be seen that
many were conf ined to a single property and did not ref lect a wider
problem in the water supply zone.

Pencil: 1 (1 BRL): this descriptor is specif ic to a substance
assoc iated with unapproved black plast ic pipe; the remedy is to
advise the householder to replace the pipe with approved medium
densit y polyet hylene pipe . A pencil odour , recorded by Brist ol W ater
at a propert y in Henleaze zone in August, was not f ollowed up wi th a
f ittings inspect ion. However, the company est ablished there was no
black pipe in the pr operty. The company reported that the consumer
had not noticed any abnormal taste and odour. Companies are
reminded that f ittings inspections ar e an essent ial part of the
evidence required to determine whet her a f ailure is due to the
domestic distr ibution system and, f ollowi ng amendment of the
regulations in 2010 , is mandator y in relation to public buildings.

Bitter/Flat: 4 (4 W SX): these descr iptors r elate to sample s where the
tap water was artif icially sof tened; the remedy is to advise the
householder to dr aw water f or drinking and cooking f rom the tap
connected direct ly to the mains (or to f it a mains f ed tap if one does
not exist) . All f our posit ive samples in the Holt zone and the
Allington zone were conf irmed as being from taps connected t o
water sof teners.

Oil/Solvent: 2 (2 BW H) these descriptors usually relate to sit uations
where there has been a spillage of central heating oil, petrol or
diesel on the pr opert y and this has permeated through the plastic
water supply pipe; the remedy is to advise the householder about
the need to replace t he aff ected pipe and to saf eguard against f uture
spills. Anot her cause of this type of taste and odour problem can be
cross connect ions bet ween cold water and central heating systems.
Bournemouth and W est Hampshire W ater traced the probable cause
21
Drinking water 2010
of a solvent taste and odour at a consum er’s tap in the Lym ington
zone to the stor age of solvents in bottles under the sink .

Earthy/ Must y: 8 (6 SW T, 2 W SX ) these descriptors relate to
situat ions where har mless , but objectionable , substances ar e
produced by the growt h of algae in raw water storage reser voirs or
the growth of f ungi in poor ly designed plumbing systems; the remedy
is impr oved treatment/reservoir management by the company or the
remedy is to advise t he householder on necessar y changes to the
design and main tenance of the plumbing system. Most of the six
earthy/must y sample reports in zones supplied by South W est W ater
in 2010 appear to the Inspector ate to be linked to works wher e there
are known problems with geosm in in the r aw water. The Inspectorate
has noted that at College works , near Penryn, Sout h W est Water
completed a legally binding programme of work in 2008 to address
taste and odour substances in the raw water. Similar ly , at Tamar
works, South W est W ater completed a programme of reservoir
management and operational measures in December 2007. The
Inspectorat e is in discussion with the com pany about these ongoing
problems. Likewise, at least one of the earthy/must y sample reports
by W essex W ater was caused by geosmin from the company’s
Porlock works. The company took the wor ks out of supply and has
since introduced new r ules regarding seasonal use of the works.

Medicinal/TCP: 1 (1 BRL) this descriptor relates to situations where
the low level of residual in the mains wat er supply is react ing with
an unapproved material; the remedy is to advise the householder
about t ypical causes , e.g. certain types of kettle, appliance h oses,
tap washers etc. Br istol W ater reported a medicinal odour f rom a
consumer ’s tap sample in the W orle and Puxton zone in March.
The company identif ied f lexible hoses connected to the washing
machine without non-return valves , but as the consumer could not
detect any odour she declined the of f er f or the installation of nonreturn valves.
W essex W ater has entered into a legally binding agreement to address
taste and odour at Blashf ord works (near Poole) by 2014. The treatment
improvements will either in volve oxidat ion by ozone or UV wit h granular
activat ed carbon ( GAC). The programme is delayed because more detailed
investigations are need ed to determine the most appropr iate solut ion .
In the inter im, the works remains out of supply. Another tast e and odour
improvement programme by W essex W ater at Sutton Bingham works is
on target f or complet ion in 2014 when over 62,000 consum ers will benef it
f rom improved water qualit y.
22
Western region
Aluminium
Alum inium can occur naturally in some drinking water sources. Also,
alum inium-based water treatment chemicals may be used at surf ace wat er
works to aid the pr ocess of f iltration.
In 2010, a total of 4,452 samples were tested f or aluminium in the W estern
region. Bournemout h and W est Hampshire W ater, Bristol W ater,
Cholderton and District W ater and South W est W ater, achieved 100%
compliance with the alum inium standard. Just one test f ailed t o meet the
standard (1 W SX) and th is was not f ound to be related to process control
at the works.
A sample taken by W essex W ater from a co nsumer ’s tap in t he Maundown
Centre zone in April exhibited a f ailure of the standard f or aluminium.
The propert y was sit uated in a cul -de-sac. Follow-up samples contained
elevated levels of iron and the company f ound evidence of manganese and
iron deposits in the supply main. The company has put in place a regular
f lushing programme to minim ise the dist urbance of histor ic m ains deposits.
Fluoride
Traces of f luoride occur naturally in many water sources, particularly in
groundwaters. For exam ple , f luoride occurs in water drawn f rom the great
Oolite limestone in t he area of North East Somerset and W est W iltshire
(particular ly around Lacock ). Consumers can obtain specif ic inf ormation on
the level of f luoride in the drinking water supply to their home or wor kplace
f rom their water com pany.
Fluoride is not removed by conventional water treatment. Some companies
f luoridate water supplies where required by the local health author it y as a
protection against tooth decay. There ar e no f luoridation schemes in the
W estern region. In 2010, all 1, 199 tests f or f luoride taken acr oss the
region met the regulatory st andard (1.5m g/l). Please ref er to the DW I
website ( www. dwi.gov.uk ) f or more inf ormation on f luoridat ion.
Lead
The pipe connecting a propert y to the wat er company main, together with
internal plum bing, is the most common source of lead in dr inking water.
Propert ies built or renovated since 1970 are unlikely to have lead pipes
and lead solder was banned f or use with copper dr inking wat er
installat ions in the early 1970’s. The only other recognised source of lead
in dr inking water in some buildings is f ittings made f rom brass. The extent
of lead pick up depends on various f actors; temperature, acidit y (pH),
23
Drinking water 2010
water hardness, t he length of pipe and the time that water is lef t to stand
in the pipe (stagnation) bef ore it is dr awn off .
The monitoring data collect ed by companies during 2010 has been added
by the Inspectorate t o that gathered in pr evious years to provide an
updated picture of progress in the region and f or the industry, towards
meeting the f uture standard f or lead of 10 µg/l by the end of 2013 (see
Figure 7).
Figure 7: Percentage of tests meeting t he current and fut ure standard
for lead betw een 2001 and 2010
Percentage meeting standard
100
99
98
97
96
95
2001
2002
2003
2004
2005
2006
2007
2008
25µg/l Regional
10µg/l Regional
25µg/l Industry
10µg/l Industry
2009
2010
Figure 7 summar ises a decade of randomised consumer tap sampling f or
lead by the industr y. The data conf irm the benef icial ef f ect of water
treatment which has been introduced over the same period. In particular,
in the W estern region, the percent age of annual t ap samples f ailing the
f uture lead standard of 10µg/l has f allen f rom above 3% in 2002 to about
0.5% in 2010.
Figure 8 shows the location of f ailures to me et the f uture standard f or lead
as recorded in 2004 and 2010. Although failures of the f uture standa rd are
f ewer, there are s ome areas of the region where the r isk of f ailure is
higher, such as around Bristol, Bath and Dorchester .
24
Western region
Figure 8: Failures of the future standard for lead in 2004 compared
to 2010
W ater companies notif y both the consum er and the relevant local author it y
whenever a f ailure of the f uture lead standard occurs. In 2010, the
Inspectorat e was not if ied of a total of two f ailures of the current standard
of 25µg/l (1 BW H, 1 SW T ) and nine f ailur es of the f uture standard ( 5 BRL,
1 BW H, 1 SW T, 2 WSX) in the region, which is ver y sim ilar to the picture in
2009.
In the W estern region, to date, t wo companies (W essex W ater and South
W est W ater) have put in place action plans under Regulat ion 28 to address
the risk of not meeting the f uture lead standard by the end of 2013.
Following the successf ul introduction of water treatment, the work of
companies needs to increasingly f ocus on raising awar eness among
vulnerable groups of people in communities wher e the risk f rom lead is
highest. The Inspect orate expects companies in the region to f urther
develop these act ion plans with bespoke ser vices , such as Anglian W ater’s
initiative which targets at risk groups identif ied by health prot ection teams
and Pr imar y Care Trusts , and of f ers a f ree lead te st with f ree replacement
of communication pipes if the sample exceeds the 2013 standard of 10µg/l.
Anglian W ater’s dedicated Lead Strateg y Team are also identif ying
opportunit ies to work in tandem wit h local authorit ies and housing
associat ions – combining their schemes t o ref urbish council or housing
associat ion owned properties with the company’s lead communication pipe
25
Drinking water 2010
replacement work; theref ore resulting in t he elim inat ion of lead pipework to
these properties.
In addition, dur ing 2010, companies in th e region have responded to
419 consumer requests to check the level of lead in dr inking water in a
particular propert y.
Nitrate and nitrite
Nitrate occurs natur ally in all source wat ers due to the decay of vegetable
material in soil. Nitrogenous f ertili sers used on arable f armland are a
signif icant source of nitrate in groundwat er. Rainf all washes nitrate f rom
the soil into lakes, river s and streams. Nitrate levels can be r educed by
water treatment or by blending with anot her, low nitrat e, wat er source.
In 2010, all 1,815 tests f or nitrate met the standar d (50mg/l).
From extensive inf ormation gathered by the water companies, a likelihood
of drinking water supplies in the region f ailing the nitrate standard in the
longer term has been conf irmed at some s ites. As a consequence, a legally
binding agreement is in place f or catchment management and the
construct ion of an integrated grid syst em to f acilitate blending , if required,
f or several W essex W ater sites: Bulbridg e, Chirton, Dunkerton, Fonthill
Bishop, Hooke, Stur minster and W ylye. The catchment management
measures are due to be delivered by Mar ch 2015 with the grid system in
place by March 2018. Similar ly, a blending scheme is to be pr ogressed by
Bristol W ater at Frome works by the end of September 2014 .
Nitr ite may be f ormed when chloram ine is used as the residual disinf ectant
to maintain the m icr obiological qualit y in the distr ibut ion net work.
The f ormation of nitrite is controlled by caref ul optim isat ion of the
chloramination process. In the W estern region, Bour nemouth and W est
Hampshire W ater practices chloram inat ion. Nitr ite can also f orm in
samples of water, af ter collect ion and bef ore analysis, especially if the
sample is not kept cool. In 2010, out of 1,813 tests carr ied out across the
region just one exceeded the nitr ite standard (1 BW H).
In May, Bournemouth and W est Hampshire W ater , when investigating a
nitrit e f ailure at a consumer’s tap in the Lym ington zone , det ected
ammonia in f ollow- up samples indicat ive of control problems at Ampress
work s. The company also identif ied poor water turnover at Lymington
tower. Bournemout h and W est Hampshire W ater are investigat ing ways to
increase turnover in the water tower in addit ion to improving the control of
ammonia dos ing at the works. The Inspectorate has noted a histor y of
f ailures in this zone and expects the company to update its regulator y risk
assessment to ref lect the control measur es in an act ion plan.
26
Western region
Pesticides and related products
This group of substances , generically called pesticides, inc ludes many
organic chemicals ranging from weed killers, to insecticides and
f ungicides. W ater sources may cont ain traces of pesticide residues as a
result of agricultur al use (pest control on crops) and non -agricultural uses
(herbicides f or weed control on highways etc.). W ater companies are
required to assess t he risk to drinking water supplies of pesticide use in
their catchments and test f or those which might be present. Companies
have document ed potential and actual pesticide hazards thr ough their
Regulation 27 risk assessments , which are inf ormed by raw water
monitor ing and identif y the control measures in place. W hen pesticides are
f irst detected, water companies will enhance their monit oring of raw water
and not if y the Environment Agency to f acilit ate appr opriate act ion to
saf eguard drinking water qualit y.
In 2010, none of the 1,165 tests in the region exceeded the st andard f or
total pesticides. Likewise, there was 100% compliance (3,615 tests) f or the
f our pesticides with a standar d of 0.03μg/l. Out of a total of 39,496 tests
f or those individual pesticides ( with a st andard of 0.1μg/l) just two (1 BRL,
1 W SX) exceeded the standar d. The circumstances and substances
involved are summarised below.
2,4-D
2,4-D is a phenoxy acid h erbicide used f or killing broad - leaved weeds in
cereal crops, turf , f orestry, orchards and non -crop areas. The standard is
0.1µg/l.
W essex W ater detected 2,4-D at a level of 0.12μg/l in a sam ple taken in
July and is invest igating cross connect ions with private supplies as the
most probable cause (see the Dr inking w ater quality events section).
Metaldehyde
Metaldehyde is the active ingredient in some slug pellet s. The standard is
0.1µg/l.
In October, metaldehyde was detected at a level of 0.10 2μg/l in a sample
f rom Purton works (near Halmore) manag ed by Br istol W ater. Metaldehyde
has been recognised as a risk in the raw water at Purton works and the
company has a legally binding agreement in place f or catchment
management activit ies.
Detect ion of metaldehyde in other catchm ents in the W estern region and
elsewhere in England has led to act ivities to improve the management of
metaldehyde in all af f ected catchments. Through the legally binding
agreements, which last until 2015 , companies are working with a variet y of
27
Drinking water 2010
stakeholders. Catchment management off icers have been recruited who
regularly meet with farmers, manuf acturers, agronomists, Nat ural England
and the Environment Agency. Since 2009 , there has been a general
decline in the levels of metaldehyde ident if ied through raw wat er
monitor ing and a growing knowledge of the prevalence and seasonalit y of
use of this substance enabling f ocused action to be taken.
Trihalomethanes
Trihalomethanes ar ise when chlorine is added to water cont aining naturally
occurring organic substances. Treatment processes are opt im ised by wat er
companies to minim ise their pr oduct ion. The regulations were amended in
2010 to require that trihalomethanes and other disinf ection by -products are
kept to a minimum whil e not compromising disinf ection. This change
transposed into law a requirement of the 1998 European Drinking W ater
Directive.
In 2010, out of 1,486 tests across the region , only f our exceeded the
standard f or trihalom ethanes (4 BRL). In September, Bristol W ater
reported f our f ailures at consumers’ taps in the f ollowing zones: Saltf ord,
Keynesham and Bitton, Yate Coalpit Heath and W armley, Stapleton, St
George and Coombe , Longwell Gr een and Oldland. All these zones ar e
ser ved by Purton works where the company identif ied a f ault with the
dosing of chlorine into the raw water. Lowering the chlorine dose reduced
the f ormation of trihalomethanes and the company have since introduced
daily checks to manage the situat ion in the short term. The company is
committed to a legally binding programme of work at Purton and at
Littleton works to minimise the f ormation of t rihalomethanes by December
2011.
Maintaining w ater quality in distribution
The parameters most commonly linked to aesthet ic wat er qu alit y problems
are iron and mang anese. These substances may be present naturally in
raw wat er sources, ir on compounds may be added as part of water
treatment or can be released as a consequence of the corrosion of iron
mains. The most severe problems tend to be wher e the distribution
net work contains a large proportion of old cast iron mains. Eff ective water
treatment reduces ir on and manganese at source, but if treatment has
been inadequate hist orical ly then iron and manganese will have
accumulated in local parts o f the distribut ion system. W hen these deposits
are dist urbed, they may cause black , brown or orange discolouration of the
water which in turn results in br eaches of the turbidit y st andar d. In 2010,
across the W estern region there were eight f ailures of the iron standard
28
Western region
(5 BRL, 1 SW T , 2 WSX) compared to seven f ailures in 2009. Also, there
were three manganese f ailures in 2010 ( SW T) compared to two f ailures in
2009. A related, but less f requen t, problem that may arise in the
distr ibut ion net work is the deter iorat ion of old coal tar linings of cast iron
mains causing f ailur es of the standards f or polycyclic aromatic
hydrocar bons, including benzo(a) pyrene. In 2010, there was one (W SX)
f ailure of the standar d of 0.01μg/l, the same as in the previous year.
Elevated levels of iron or manganese ar e objectionable to consumers
because the water may appear turbid, it may have an astringent or bitter
taste and the deposits are unsightly and may stain water f ittings.
Since 1996, the Inspectorate has been measur ing the progress of
companies ’ distribut ion maint enance wor k to address these problems wit h
an index made up of the three param eters (iron, manganese and turbidit y).
Figure 9 shows the improvements generally over the past 15 years with the
last three years achieving 99.95% or greater across the region.
Figure 9: Percentage of tests meeting t he standards for turbidit y, iron
and manganese
100.00
Percentage meeting standard
99.50
99.00
98.50
98.00
97.50
97.00
96.50
96.00
95.50
95.00
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Bournemouth and West Hampshire Water
Bristol Water
Cholderton and District Water
South West Water
Wessex Water
Note: SSE W ater only began supplying water in 2008 . They have achieved 100% in each year
since.
Veolia W ater Projects only began supplying water to Tidworth in 2009. They have achieved 100%
in each year since.
Discolourat ion of water supplies of ten prompts consumers to contact their
water company. The rate of contacts in 2007 and 2010 f or each supply
zone is mapped in Figures 10 and 11.
29
Drinking water 2010
Figure 10: Rate of consumer contacts per 1,000 population reporting
black, brow n or orange w ater in 20 07
Figure 11: Rate of consumer contacts per 1,000 population reporting
black, brow n or orange w ater in 2010
30
Western region
The two maps illustr ate the improvement s made over the f our -year per iod
in reducing discolour ation contacts in the W estern region, particular ly in
Cornwall and the ar eas around Exeter and Devizes .
In 2010, there were f ive f ailures of the iron standar d in zones operated by
Bristol W ater : (Stapleton St George and Coombe zone, Cit y Centre St
Philips and Netham zone, Hengrove and W hitchurch zone, Hawkesbur y
W ickwar Alveston and Charf ield zone and Knowle and St Annes zone ).
All f ive zones are scheduled to be included in a legally binding programme
of mains replacement and cleaning. The company has been f unded to carr y
out this work in the AMP5 per iod (2 012–2015) and the Inspectorate will be
closely scrutinising the deliver y of this work by Bris tol W ater.
The three remaining f ailures ( 1 SWW , 2 W SX) each in dif f erent zones
(Bratton Fleming Sz, Hampton Down and Upton Scudamore ) were due to
a localised disturbance of mains deposits dealt with by f lushing.
Three manganese f ailures arose in zones o perated by South W est W ater .
A f ailure in the Prewley zone in August was linked to higher than usual
levels of manganese at the Prewley works. The company undertakes pH
correction at this sit e and this was opt imised to f acilitate manganese
removal. A nother f ailure in November was in the Littlehemptson, Tottif ord,
Bovey Cross zone where the company has a legally binding programme of
work to install treat ment f or manganese removal at Tottif ord works by
March 2012. Elevated manganese was also detected in a sam ple f rom
Restormel East zone in December and was attribut ed to mains sedim ent
mobilisation f ollowing a mains burst which was clear ed by f lushing.
In May, W essex W ater detected b enzo(a) pyr ene in a consumer’s tap
sample f rom Sutton Bingham zone. Following a n investigation of the mains
pipework , the company identif ied a mixture of cement and epoxy lining ,
and concluded th at benzo(a)pyrene was linked to a length of coal tar lined
main upstream. The main in question is to be replaced or re -lined. The
company has implem ented enhanced monitoring and added the new
inf ormation to its regulator y r isk assessm ent. The Inspectorat e notes that
this zone is scheduled f or improvement work to address iron and
manganese f ailures in the AMP5 period.
Annex 4 details the legal ly binding programmes of distribut ion
maintenance work scheduled to be completed bet ween now and 2015
to address cont inuing distribut ion qualit y problems in the region.
31
Drinking water 2010
Drinking water quality events
W ater qualit y events are classif ied into f ive broad categories based on the
initial company repor t . The categories are:
Not significant: no f urther inf ormation required by an inspect or to assess
the event.
Minor: it is unlikely t hat f urther inf ormation would be requir ed by an
inspector to assess t he event .
Significant: a f ull company report may be required to enable an inspector
to assess the event .
Serious: in addition to a f ull company report, the assessment may require
action by more than one inspector and a resultant invest igation.
Major: in addit ion to a f ull company r eport, the assessment is likely to
involve an investigat ion led by senior inspectors requir ing ext ensive
inf ormation gather ing and wide ranging investigat ions.
In 2010, companies in the W estern region notif ied the Inspect orate of
42 events. Table 12 shows how these events were classif ied.
Table 12: Water qualit y events in the region in 2010
Nat ur e of ev e nt
A ir i n wa t er
Ch em ic a l
Dis c o l our e d wa t er
In a de q ua te t r e atm en t
Los s of s u p pl i es / p o or pr es s ur e
M ic ro b i ol o g ic a l
T as te /O d o ur
He a lt h c o nc e r n
P ub l ic c o nc er n
O th er
Reg ion ov er al l
Eng l and an d W al e s
Ri sk as s es sm ent cat ego r y ( DW I)
M inor/no t Si gnif i ca nt
M ajor/ s e rio us
sig nif ic ant
20 0 9
20 1 0
20 0 9
20 1 0
20 0 9
20 1 0
3
1
1
1
5
3
5
5
1
1
6
7
1
1
8
1
5
5
1
1
1
4
8
2
1
2
2
1
23
25
17
16
1
1
27 6
22 2
14 1
16 0
5
9
A summar y of the nature, cause and dur ation of each event categorised as
signif icant, serious or major , along with details of the Inspect orate
f indings, are set out in Annex 3. Most events were of relat ively short
duration and the company took appropriate acti on at the tim e to inf orm and
saf eguard consumer s and other stakeholders. A compar ison of 2009
events with those of 2010 shows the num ber of signif icant, serious and
major events was similar to last year (17 compared to 18 ).
32
Western region
The region experienced one serious event in 2010 when a propert y was
connected to a sewer instead of a water main. The circumstances of this
event are detailed in Connection of property to a sewer i nstead of a water
main. W ider learning points f rom event investigations in the r egion in 2010
are highlighted by the f ollowing cases:
Connection of propert y t o a sew er instead of a w ater main

A connection to a newly built house was carried out on 7 July .
On 9 July the builder was not if ied by a plumber commissioning the
boiler/hot water syst em of discoloured water with a strange smell in
the propert y. The builder dr ove to the local of f ice of W essex W ater
in Salisbur y to repor t the situat ion. A company ins pector attended
the site and disconnected the supply which was conf irmed to be
contaminated by analysis of samples. Fortunately , nobody had used
the water f or domestic purposes and W essex W ater took remedial
action. The sewer belonged to Southern W ater and W essex W ater
has now revised its procedures to impr ove the accuracy of its own
water and wast e wat er assets and to ensure that wider checks are
undertaken bef ore any new water mains connections are made. (see
Annex 3). The misconnect ion of a propert y to a sewer is an er ror
with potent ially ver y serious consequences f or public health and the
Inspectorat e is ver y concerned that this is the second year in a row
when such an event has occurred in the industr y.
Pri vate w ater supplies as a possible cause of pes ticide contamination
of public w ater supplies

This event relates to intermittent detection of 2,4 Dichlorophenoxyacetic acid (2,4 - D) in consumer tap samples.
Af ter a thorough assessment of the raw water source f ailed to
identif y a source in t he catchment , W essex W ater’s attention has
turned to invest igating the possibilit y that the contamination is
arising f rom cross connect ions bet ween t he public distribution
net work and the many pr ivate supplies in the area (see Figure 13) .
This hypot hesis is being syst emat ically investigated in collaboration
with the local authority. A n Environmental Health Off icer was
seconded to W essex W ater f or three months to f acilit ate the
investigation. The Inspectorate is pleased to acknowledge this
example of joint wor king and b etter regulation. W essex W ater are in
the process of submitting an undertaking which will produce an
action plan to det ermine the source and pathway f or 2,4 -D entering
the public wat er supply system.
33
Drinking water 2010
Figure 1 3: Illustration of public netw orks and potential pri vate
netw orks
The off ence of supplying water unf it f or human consumption is under
considerat ion f or one event that occurred in the W estern region in 2010.
Technical audit activity
The Inspectorate has operated a risk -based approach to technical au dit
since 2005. In line with better regulation principles, no technical aud it
takes place wit hout a reason .
The Inspectorate’s t ool f or generating the technical audit pr ogramme loo ks
at the critical components of the saf e management of drinking water
supplies, including inf ormation on water qualit y monitor ing, event
assessments, previous audits, consumer complaints and ot her relevant
intelligence. Through this ranking of all relevant water company assets,
procedures and practices , inspectors are able to prior itise and f ocus their
technical audit work where it will have m ost benef it . The resultant audit
programme f or 2010 is shown in Table 14 . The Inspectorate also carried
out an audit related to analytical malpr act ice at a laborator y operated by
Severn Trent Ser vices who analysed samples f or Bristol W ater and SSE
W ater in the region.
34
Western region
Table 14: Summary of the Inspectorate ’ s technical audits i n the region
Sit e n am e
Au di t t o pi c
M ain fin din gs f rom a udit
C o l if or m
bac t er i a
G e ner a l l y s at is f ac t or y
 M in or is s u es i de n t if i ed wit h m oni t or in g of
res id u a l c h lor i n e i n on e c om par tm ent of c o nt ac t
ta nk .
Br is tol Wa t e r
Ch e dd ar
work s
S ev e rn Tr ent S er v ic e s – An al yt ic al Se r vi c es Ltd
Br i dg e nd
l ab or at or y
A na l yt ic a l
m alpr ac t ic e
A ud i t de em ed u ns at is f ac t or y – s u bs eq u en t
i n ves t ig at i o n on g o in g
 Rec om m end a ti o ns we r e m ad e i n res p ec t of
i nor g an ic c h em ic a l a n a l ys is f or t he wa ter
un d ert ak ers or t he c o m bin ed l ic e ns ees in f a i l in g
to m eet t h ei r ob l i ga t io ns u nd er R eg u l at i ons 16
an d 3 4 f or a na l ys is of wa ter s am pl es an d , i n
par t ic u l ar , de ri v e d a n a l yt ic a l d at a, c om p et en c y,
ret e nt i on of a p pro pr i at e r ec ords an d f or th e
ap pr o pri a te t im e us in g s u i ta b le eq u ipm e nt .
 T he Ins p ec t or at e r em i nd e d c om pa n ies t h at i t is
th e d ut y of t he wat er u nd er tak er or t h e
c om bi ne d l ic e ns e e t o ens ur e th e y ar e c om p l i an t
an d t h is c an n ot b e d ef err ed t o a t h ird par t y
l ab or at or y.
 Rec om m end a ti o ns we r e m ad e t o ens ur e t ha t th e
pro v is i o n of inf orm at i o n as p art of t he
c om pan i es re g u la tor y du t ies m us t b e
dem ons tr at e d to b e a t rue r epr es e nt at i on of a
rob us t an d ac t ua l a n al yt i c a l pr oc ed ur e.
 Rec om m end a ti o ns we r e m ad e f or th e f ut ur e
a vo i d anc e of br eac h es of th e r e g ul a t io ns
req u ir i ng t h e l ab or at or y , t hr o ug h t he d u t ies o f
th e s t at ut or y u nd er tak ers , t o im p lem en t a nd
m aint a i n a s ys t em of o per a ti o n al m an ag em en t
c o ver i n g a n um ber of are as , bu t i nc l ud i ng
rob us t, t im el y, ef f ec t i v e a nd res p o ns i v e us e of
qu a l it y s ys t em s , c a p ac it y m a n ag em en t an d
i nd e pe n de nt bus i n es s an d q u al i t y o bj ec t i ves .
 E nf orc em ent ac t io n t a k en in r es p ec t of e i g ht
c om pan i es us i ng t h e l ab or at or y f or c h em ic a l
an a l ys is of r eg u l at or y dr i nk i n g wa ter s am pl e s .
 Fu l l de t a ils are t o b e p ro v id e d i n th e f orm of a
pu b l is h e d a ud i t r e por t an d wi l l be a va i l ab l e o n
th e I ns p ec t or at e ’s we b s it e o n c om pl e ti o n of t he
i n ves t ig at i o n .
35
Drinking water 2010
Sit e n am e
Au di t t o pi c
M ain fin din gs f rom a udit
Sout h W e st W at er
A nt on y
res e r vo ir
Co l if or m
bac t er i a
Mo or h a ve n
res e r vo ir
Co l if or m
bac t er i a
Up to n
res e r vo ir
Co l if or m
bac t er i a
B ol v e nt or
res e r vo ir
Co l if or m
bac t er i a
Do us la n d
work s
Co l if or m
bac t er i a a n d
E.c o l i
P ort wor t h y
res e r vo ir
Co l if or m
bac t er i a a n d
E.c o l i
G e ner a l l y s at is f ac t or y
 Rec om m end a ti o ns m a de ab o ut g e ner a l
def ic ie nc ies wi th c om pan y a p pr oac h t o r es er v o ir
m aint e n anc e a nd wa te r q u al i t y m an a gem e nt
s tra te g y
G e ner a l l y s at is f ac t or y
 Rec om m end a ti o ns m a de ab o ut g e ner a l
def ic ie nc i es wi th c om pan y a p pr oac h t o r es er v o ir
m aint e n anc e a nd wa te r q u al i t y m an a gem e nt
s tra te g y
G e ner a l l y s at is f ac t or y
 Rec om m end a ti o ns m a de ab o ut g e ner a l
def ic ie nc ies wi th c om pan y a p pr oac h t o r es er v o ir
m aint e n anc e a nd wa te r q u al i t y m an a gem e nt
s tra te g y
G e ner a l l y s at is f ac t or y
 Rec om m end a ti o ns m a de ab o ut g e ner a l
def ic ie nc ies wi th c om pan y a p pr oac h t o r es er v o ir
m aint e n anc e a nd wa te r q u al i t y m an a gem e nt
s tra te g y
Uns at is f ac t or y
 T he m ai n c ri t ic is m s were ab o ut t h e l ac k of r a w
wa ter m on it or i ng t o i nf orm op er at i o n of t h e
work s , l im it ed prof i li n g of s a nd in t h e f i l te rs an d
l ac k of c le a ns i n g af t er a c o n tac t ta nk i ns pec t i on .
 Rec om m end e d th e tr e at e d wa ter t a nk was ta k en
ou t of s up p l y f or i nt e g rit y c hec k s .
S at is f ac tor y
 A l l r em ed i al ac t i ons id en t if i ed in t h e c om pa n y’ s
i ns p ec t i o n r e por t h ad be e n c om pl et e d
Public confidence in drinking water quality
Consumer contact s to w ater companies
W hen consumers have a question or a concern about dr inking water
qualit y their f irst point of contact is the water company. All companies
record these contact s using def initions agreed with the Inspectorate.
The Inspectorate has been collect ing consumer contact inf ormation f rom
the industr y f or a number of years. Figur e 1 5 illustrates the improving
picture in England, with a 29% reduction over f ive years in the numbers of
consumers reporting a problem with their tap water (now about 98, 000
compared to 138,000 in 2006). O ver the same time f rame, the W estern
region has seen a 43% redu ction in contacts with about 18,000 recorded in
2010 compared to over 31,000 in 2006. The W estern region has been a
36
Western region
major contributor to the improved posit ion in England as a whole. In 2006 ,
a quarter of all contacts arose in the W estern region but the improvements
since 2006 mean that the W estern region now contributes one -f if th of the
total and the contact rate is down f rom a peak of 7.3 to 3.9 per 1 ,000
populat ion.
Figure 15: Total consumer contact s for appearance, taste and odour,
illness 2006–2010
160,000
Consumer contacts
140,000
120,000
100,000
80,000
Western region
Other regions
60,000
40,000
20,000
0
2006
2007
2008
2009
2010
Looking in more detail at the inf ormation, the most commonly r eported
concern in the W estern region remains, by a large margin, discoloured
water (black, brown or orange). However , the improving trend means that
in 2010 the number of contacts was 10,400 compared to 22,000 in 2006
(see Figure 16). The main benef iciaries have been customer s of South
W est W ater. Maps in the Maintaining water quality in distr ibut ion section
illustrate, on a zone - by- zone basis, the level of consumer cont acts in 2007
and 2010, and progress to date is clear ly visible.
37
Drinking water 2010
Figure 16: Numbers of consumer cont acts 2006 –2010
35,000
Consumer contacts
30,000
Total (appearance/taste
and odour/illness)
25,000
20,000
Black, brown or orange
water
15,000
White water due to
entrained air
10,000
Chlorine taste or odour
5,000
0
2006
2007
2008
2009
2010
W hite water due to entrained air and chlorine -related tastes and odours
are also common consumer concerns , and the improvement in white water
contacts has been small in 2010 . Also, the picture in relation to taste and
odour is rather var iable. The only company to exhibit a strong downwar d
trend in white water conta cts over the last f our years is South W est W ater.
The Inspectorate expects companies to use cont act data to analyse events
in the net work to improve oper ational practices and ther eby m inimise the
impact on consumers.
Consumer complaints to the Inspectorat e
W hen the response of a company to a consumer contact about drinking
water qualit y f ails to provide the necessar y reassurance or remedy then
the consumer may contact the Inspector ate f or advice. In 2010, there were
six consumers suf f iciently dissatisf ied with the water company’s init ial
response to their complaint to raise the matter f urther with t he
Inspectorat e. The reasons f or contacting the Inspector ate are provided
in Table 17.
38
Western region
Table 17: Cont acts from consumers recei ved by the Drinking
Water Inspectorate
Cat ego r y
Numb e r of cont a ct s
A pp e ara nc e
1
T as te a n d od o ur
4
Re p ort of i l l nes s
W ater q ua l i t y c o nc er n
1
Num ber of c o nt ac ts to DW I f r om c ons um ers b y c om pa n y.
BR L (2) , SW T ( 4)
Categories are as defined in Information Letter 1/2006.
Figure 18 depicts the numbers of complaints received by the Inspectorat e
f rom consumers in the region since 2002 in the context of the total
complaints received f rom consumers in England and W ales . The f igure
illustrates a generally improving trend in the W estern region since 2005 ,
which f ollows that f or the industr y as a whole, although the Inspectorate
notes there were more complaints in 2010 compared to the pr evious year
(6 compared to 3).
Figure 18: Complai nts recei ved b y DWI from 2002 to 2010
180
160
Consumer contacts
140
120
100
Western region
80
Other regions
60
40
20
0
2002
2003
2004
2005
2006
2007
2008
2009
2010
Case exampl e
In Januar y, a consumer f rom Bristol W ater contacted the Inspectorate
complaining her wat er was cloudy and slim y , and it was af f ecting the
condition of her hair, nails and skin. The consumer had been in regular
contact with Br istol W ater over sever al mont hs and was unhappy because
she had obser ved an improvement in her symptoms when visit ing f riends in
39
Drinking water 2010
other parts of Bristol. The company had explained that this may be a
matter of perception caused by a diff erence in the hardness of the water
bet ween the t wo zones wher e her home and that of her friends were
situated. Bristol W ater carried out a f ittings inspect ion at the block of f lats
where the consumer lived. S everal def iciencies were ident if ied, particular ly
in relat ion to the common hot water syst em, whi ch the owner was required
to rectif y. This case is an example of the way in which water qualit y
complaints can be misdiagnosed . W hen a company is over ly f ocused on
counter ing the negat ive percept ions of a consumer , there is a risk of
f ailing to recognise t hat a report of unusual water qualit y in a building is
being made which warrants a prompt technical invest igation.
Planned drinking water quality improvements
Securing safe, clean drinking w ater through the application of a
risk-based approach to regulat ion
The publication of Drinking water 2010 m arks an important milestone in the
histor y of drinking water regulation , nam ely the 20- year anniver sar y of
implementat ion by g overnment of the EU Drinking W ater Directive.
It records how the regulator y regime ha s been applied successf ully and
improved upon since. In particular, the regulator y f ramework now goes
beyond rectif ying def iciencies in drinking water qualit y by convert ing t wo
decades of essential investment in water treatment and distribution into
sustainable improved drinking wat er supplies through operat or risk
assessment and t imely preventat ive action incent ivised by independent
oversight and f irm , but f air, sanctions.
40
Western region
2.5
Figure
19: The percentage of tests failing the standards from
1991 to 2 010
Percentage of samples failing in zones
2
1.5
1
0.5
0
England and Wales
Scotland
Northern Ireland
The purpose of drinking water regulation is to secure saf e , clean drinking
water f or all and this outcome is measured objectively by the I nspector ate ,
using ver if ied scient if ic data (Figure 19) alongside data to conf irm the
benef it in the f orm of con sumer reports about tap water qualit y (Figure 20).
These outputs ar e measured at the tap and theref ore provide ver if icat ion
of the eff icacy of all the hist orical invest ment and operational management
actions taken at ever y point throughout a supply system f rom source to
tap.
Figure 20: The total amount of consumer contacts for appearance,
taste, odour and ill ness from 2006 to 2010
160,000
Consumer contacts
150,000
140,000
130,000
120,000
110,000
100,000
2006
2007
2008
41
2009
2010
Drinking water 2010
The principal regulat ory enf orcement tool that has enabled this
improvement in dr ink ing water qualit y has been the putting in place of
legally binding programmes of work to address clear ly ident if ied and
specif ic def iciencies by the Inspectorate. Over 20 years these
‘undertakings’, given under Section 19 of the W ater Industry Act 1991 ,
have enabled water companies to design and deliver technically
appropr iate asset improvement schemes. An u ndertaking comprises a
schedule of sequential remedial steps; typically these will be an
investigation, f ollowed by changes to the operation of a treatment
works/supply system or the installat ion of new treatment equipment at a
works or the renovat ion/replacement/cleaning of water mains. The
schedules set delivery dat es f or each milestone step with reporting
requirements f or progress monitoring and demonstration of benef it, i.e.
that the outcome req uired has been achieved.
In 2004, the W orld Health Organisation ( W HO) published the water saf ety
plan appr oach as the most eff ective means of securing a suff icient supply
of saf e, clean dr inking water f or all. In 2005, the Inspectorat e adopt ed the
water saf ety plan approach as its strategic policy f or developing the
regulator y regime f or drinking water f irst introduced by Parliament in
England and W ales in 1990. In 2007, the drinking water regulations in
England and W ales were amended to f ormally embed this r isk -based
approach into the legal f ramework.
These amendments included provision f or R egulat ion 28(4) Notices, a new
enf orcement tool that is now converting two decades of invest ment in
improvement into sustainable supplies of saf e , clean dr inking w ater.
These Not ices set out the steps that are necessar y to mitigat e
unacceptable residual risks. A Notice typically specif ies the f ollowing types
of actions: additional improvements or maintenance, regular reviews and
audits of operational controls, cond itions under which use of a supply is
prohibited, managem ent and other inf ormation requirements and report ing.
The principal dif f erence bet ween the t wo enf orc ement tools is that
undertakings are generally f ailure dr iven , whereas Not ices ar e risk -based
and preventat ive. Undertakings are used where a f ailure has occurred and
is considered likely t o recur, identif ied usually through the audit act ivit y of
the Inspector ate, or as part of a water company’s business planning
processes. Not ices, by contrast, ar ise out of a process of continuous risk
assessment carried out by wat er companies where the Inspectorate
acknowledges the m anner by which ident if ied risks are being mitigated and
controlled. If necessary f or the protection of public health, certain controls
or remedial actions can be audited, imposed or made mandatory.
Both enf orcement tools ser ve as an incentive to improve drinking water
supplies and to prot ect consumers. Furthermore, as a consequence of
putting risk assessm ent at the heart of the new enf orce ment tool, the
42
Western region
ext ent to which risk management and r isk prevent ion are becoming
embedded in the industry can be measur ed object ively by the recording of
acknowledged act ion s to mitigate risk.
Across the industr y, there are currently 469 mandat or y schem es
document ed in the r eport ( Annex 4) wher e enf orcement has been used to
improve those f ew water supplies that continue to f ail to meet drinking
water standards (undertakings) or to mitigate previously unrecognised
risks which pose a potential danger to human health (Not ices). In addit ion,
there are 516 other preventat ive actions identif ied by water companies
through risk assessment and acknowledged by the Inspect orate. Table 20
ref lects the progress of the industr y in delivering these acknowledged
preventat ive actions. Together all these data can be used to demonstrate
the extent to which a proactive preventat ive approach to the management
of drinking water qualit y has become em bedded in wat er companies as a
result of the switch to mandator y r isk management. F or exam ple, more
than half (52%) of the 985 improvement actions identif ied as necessar y at
the end of 2008 ar e being delivered voluntarily, without the need f or
enf orcement action by the Inspector ate.
Table 21: Acknow ledged a ctions to sustain safe , clean dri nking w ater
Reg ion
Ce ntr a l
E as t er n
Nor th er n
S ou th er n
T ham es
W es tern
W ales
T otal
Ad di t io na l a ck now led ged
act ion s t o mit ig at e ri sk
( as at De c 2 0 08)
0
10
44
51
62
38
31 1
51 6
Ac k now l edg e d a ct ion s
com pl et ed ( a s at D ec 2 0 10)
0
1
15
20
36
25
35
13 2
Note: The Central region figures do not include Dŵr Cymru W elsh W ater. The figures for the
Northern region do not include Dee Valley W ater. The figures for W ales do not include Severn
Trent W ater.
Mitigating risks at source through catchment management
An important element of the risk assessm ent process carried out under the
Regulations is the character isat ion of hazar ds within catchments,
determining where these pose a risk to the qualit y of a specif ic drinking
water supply and how they will be mit igate d through actions in the
catchment to protect or improve raw water qualit y. Ar ising out of this work
a number of companies now have catchm ent manage ment schemes as a
component of u ndertakings and catchment management activities may be
specif ied in Not ices or in acknowledged action plans. The dir ect benef its of
43
Drinking water 2010
catchment managem ent are the pot ential f or removing the need f or costly
provision, or replacement, of water treatment or f or reducing operat ional
expendit ure in relation to treatment alr eady in place. These schemes also
provide wider benef its where they result in improvements to the natural
environment.
A typical example is a scheme or act ion plan where the wat er company
commits to carr ying out an invest igation to pin point the source of specif ic
contaminants (such as nitrate, one or more pesticide s, or colour as a
precursor of disinf ection by- products) by setting up a working partnership
with local stakeholders such as the Envir onment Agency , f armers, land
managers or agronomists , f or example, to alter the way in which a pr oduct
is being applied to land. The company will carr y out targeted r aw water
monitor ing and contribute other resources to set up and f acilitate the work
of the partnership. Table 22 summar ises the catchment management work
in the W estern region in relat ion to the drinking water qualit y parameters.
Table 22: Catchment management acti vities in the region
Comp an y
T reat m ent w o rk s w h e re
re gul at ed c at chm ent
man ag em ent i s in p la ce
Ri sk b ei ng mit ig ate d
B our n em out h a n d W est
Ham ps h ir e W ater
0
N/ A
Br is t o l W ater
3
Me t al d e h yd e ( 3)
Ch o ld er to n a n d Dis tr ic t
W ater
0
N/ A
S ou th W es t W ater
0
N/ A
S S E W ater
0
N/ A
V eo l i a W ater Pr oj ec ts
Lt d
0
N/ A
W es s ex W ater
8
Reg ion ov er al l
11
Ni tr at es ( 7)
Me t al d e h yd e ( 1)
M etald eh yde ( 4)
Nit r ate s (7)
For further inf ormation on the Water Supply (Water Quality) Regulations
2000, or the m icrobiological and chemical parameters covered by the
regulations please r efer to the DWI website ( www.dwi.gov.uk ).
If you have a need f or more specific information than that on our website,
please contact us on the DWI enquiry line: 030 0068 6400 .
44
Western region
Annex 1
Further sources of information
The publication Dr inking water 2010 comprises the regional r eports f or
England and a report covering W ales. There are six r egional r eports f or
England (Central, Eastern, Northern, Southern, Thames and W estern) and
one f or W ales (in t wo languages). Each r eport presents inf ormation f rom
2010 under the f ollowing headings:








Introduction to the r eport.
W ater supply arrang ements.
Drinking water qualit y te st ing.
Drinking water qualit y results.
Risk assessments.
Drinking water qualit y events.
Technical audit activit y.
Public conf idence in drinking water quality.
There are also separ ate reports covering private water supplies, one
cover ing England a nd one covering W ales.
The reports and other content are published on the DW I website
(www. dwi.gov. uk).
Content of the CD
The CD supplied wit h the printed report holds all of the above content and
additionally it contains:
Water company look -up tables
These summarise all the results of water company monitor ing in 2010.
They provide inf ormation on:




what was tested;
how many tests were perf ormed;
the range of the results of testing; and
how many tests f ailed to meet the standards.
Significant drinking w ate r quality events in England and
Wales 2010
To promote shared learning, the Inspect orate has compiled a list of all
events that occurred in 2010 which illustr ate the nature and cause of each
event, the main act ions by the company and f indings f rom the insp ectors’
assessments. Relevant content f rom this overall list is contained in an
annex to each regional report.
45
Drinking water 2010
Annex 2
Glossary and description of standards
These def init ions will assist the understanding of the report where
technical terms have been used .
µg/ l
m ic rogr am pe r l itr e (o ne m il l i on t h of a gram
per l itr e).
1, 2- D i chl or oet ha ne
is a s o l v en t t ha t m a y b e f o u nd in gro u nd wa t e r i n
th e v ic i n it y of i nd us tr i a l s it es . W here n ec es s ar y
it c an b e rem o ve d b y s pec i a l wa t er tre a tm ent .
A E ur op e a n he a lt h - b a s ed s t a nd ar d of
3μ g/ l a p pl i es .
Ac r yl am id e
E uro p ea n h e al t h - b as e d s ta n dar d . A m onom e r is
no t n orm al l y f ou n d i n dr ink i n g wa ter . It is
pr o d uc ed in t h e m an uf ac t ur e of p o l ya c r yl am i des
oc c as i o na l l y us e d i n w at er tr ea tm ent .
Its pr es enc e i n dr i nk in g wa t er is l im it e d b y
c on tr ol o f t he pro d uc t s pec if ic a t io n. St a nd ar d
is 0 .1 µg / l.
Ae s th eti c
as s oc i at e d wi t h th e s e ns es of t as t e, s m el l
an d s i g ht .
Ag g re s siv e
a term us e d to in d ic at e th a t t h e wa t er h as a
te n de nc y t o d is s o l v e c op p er ( a nd ot he r m et a ls )
f r om the in n er s urf ac e of a p i pe or wa ter f i tt i ng
s uc h as a ta p .
Al k a li
a s o lu t io n c o nt a i n in g a n ex c es s of f re e h yd ro x yl
i ons , wi t h a p H gr ea te r t ha n s e v e n.
Al u min iu m
oc c urs na tu ra l l y i n s o m e s ourc e wat ers . I t i s
r em ov e d f rom dr i nk in g wat er b y c o n v en t io n a l
wa ter t re atm e nt (c o a g u la t io n a nd f i l tra t io n) .
A lum i n ium s u l ph a te a n d p ol ya l um i n ium c h l or i de
m a y be us e d as wat er tre atm e nt c h em ic a ls a t
s om e wat er tr e atm en t work s . A n a ti o na l s t a n dar d
of 2 0 0 μ g/ l a p pl i es .
Am m oni um
s a lts ar e n at ur a ll y p re s en t i n tr ac e am o un ts i n
m os t wat ers . T h e ir pre s enc e m ig ht i n d ic a te
c on t am in at i on of s a n it ar y s i gn if ic a nc e a nd t h e y
i nt erf er e wi t h th e o p er at i on of t he dis i nf ec ti o n
pr oc es s . A n i nd ic at or par am et er wi t h a g u id e
v a lu e of 0. 5m g/ l.
46
Western region
An a l yti c al qu al it y co nt ro l
( AQ C)
th e m et h od us e d t o en s ure t h at l a b ora t or y
an a l ys is m et h ods ar e perf orm in g c orr ec t l y.
An ti mon y
is r ar e l y f o u nd in dr ink i ng wat er .
T rac e am ou nts c a n b e d er i ve d f rom br as s ta p
f itt i n gs an d s o l de rs . A E uro p ea n h e al t h - b as e d
s ta n dar d of 5 μ g/ l a p p li es .
Aq ui fe r
wa ter - c o nt a i ni n g u nd e rgr ou n d s tra t a.
Ar s e ni c
oc c urs na tu ra l l y i n o n l y a f e w s ourc es of
gro u n d wat er. S pec if ic wa ter t re atm e nt is r eq u ire d
to rem o v e it . A Eur o p e an he a lt h - bas e d s ta n d ard
of 1 0μ g /l ap p l ies .
Au tho r is ed d ep art ur e
au t hor is at i o n f or a wa t er c om pa n y to t em por ar il y
s up p l y wa t er ex c ee d i n g a dr i nk in g wa t er
s ta n dar d, gra n te d b y t he au th or i ti es o n l y wh en
th er e is n o r is k t o h um an he a lt h.
Benz en e
is pr es e n t i n p etr o l. I t is n ot f o un d i n dr i nk in g
wa ter , b ut it c a n m i gr a te t hr ou g h u nd er gro u n d
p las t ic wa te r p ip es if p etr o l is s p i lt i n t h e v ic i n it y.
S om e b ot t le d wat ers a nd s of t dr ink s wh ic h
i nc l u de s od i um be n zo at e as a n i n gre d i en t h a ve
be e n r e por t ed as c on t a in i ng be n ze n e .
A E ur op e a n he a lt h - b a s ed s t a nd ar d of 1 μ g/ l
ap p l ies .
Benz o(a ) p yr en e
is o ne of s e v er a l c om pou n ds k n o wn as p o l yc yc l i c
arom at ic h yd r oc arb o ns (P A Hs ) . T h ei r s ourc e i n
dr ink i n g wa ter is as a res u l t of de te ri or at i o n of
c oa l t ar, wh ic h m an y y ears ag o wa s us ed t o l i ne
wa ter pi p es . D u e to ex te ns i ve wa t er m ai ns
ref ur b is hm en t a nd r en e wa l i t is n o w r are t o
de t ec t t h is s ubs t anc e i n dr ink i n g wa t er.
A E ur op e a n he a lt h - b a s ed s t a nd ar d of
0. 0 1μ g/ l a pp l i es .
Bo ron
i n s urf ac e wa t er s ou rc es c om es f rom i n dus tr i a l
d is c h ar ges or f rom d et erg e nts in tr e at e d s e wag e
ef f lu e nts . T h e v er y l o w c onc e ntr at i o ns f o u n d i n
s om e dr i nk in g wat ers are no t a c o nc ern t o
pu b l ic h ea l th . A Eur o p ea n h e al t h - b as ed s t a n dar d
of 1m g/ l a p p li es .
47
Drinking water 2010
Br om ate
c an be f orm ed d ur i ng d is i nf ec t io n of dr ink i n g
wa ter t hr o ug h a re ac ti on be t we en n a tur a l l y
oc c ur ri n g br om id e a nd s tr on g ox i d an ts ( us ua l l y
o zo n e). I t m a y b e ge n era t ed in t h e m an uf ac t ure
of s o d i um h yp o c hl or i te d is i nf ec t a nt .
Ex c ep t io n a ll y, gr o un d wa ter be n ea t h an in d u s tri a l
s it e c a n b ec om e c o nt a m inat e d wi t h br om ate .
A E ur op e a n he a lt h - b a s ed s t a nd ar d of
10 μg / l a pp l i es .
Bul k su ppl y
wa ter s up p l ie d i n b u lk , us u al l y i n tr e at e d f or m ,
f r om on e wa te r c om pa n y to an ot h er.
Cad mi um
is r ar e l y d et ec t e d i n dr i nk in g wa t er a nd tr ac e
am oun ts ar e us ua l l y d ue t o d is s o lu t io n of
im pur it i es f r om pl um bi ng f i tt i ngs . A E ur o p ea n
he a lt h - b as e d s t an d ard of 5 μ g/ l a p p li es .
Cat ch me nt
wh e n us e d i n c o n nec t i on wi th wa ter , th e
c atc hm ent is th e ar e a dra i n ed b y a r i v er or wat er
bo d y.
Chlo r am in at i on
th e pr oc es s of g e ner a t i ng a c hl or am in e
d is i nf ec ta n t r es id u a l i n wa t er l ea v i n g a
tr e atm e nt work s .
Chlo r am in e
a s u bs t anc e f orm ed b y a re ac ti o n b et we e n
c h lor i n e an d am m oni a, us e d as a d is inf ec t an t i n
d is tr i bu t io n s ys t em s b ec a us e of its lo n g - las t i ng
pr o p ert i es c om par e d t o c h lor i n e.
Chlo r id e
is a c om po n en t of c om m on s a l t. I t m a y oc c ur i n
wa ter na tu ra l l y, bu t i t m a y als o b e pr es en t d ue t o
l oc a l us e of de - ic i n g s a lt or s a l i n e i ntr us io n .
A n i nd ic at or p ar am ete r wit h a g u i de v al u e
of 2 5 0m g/l .
Chlo r in e r es idu al
th e s m a ll am oun t of c h l ori n e or c h l or am in es
pr es e nt in dri nk i ng wa ter t o m a in t a i n i ts q ua l it y
as i t pas s es t hro u g h t he wa ter c om p an y’ s
ne t work of p i pes a n d h ous e ho l d p l um bi ng .
Ch rom ium
is n ot pr es e nt i n dr i nk i ng wa ter . A Eur o pe a n
he a lt h - b as e d s t an d ard of 5 0 μ g/ l a pp l i es .
Clo st ri diu m p e rf rin ge ns
is a s p or e - f orm in g b ac ter i um th at i s pr es e n t i n
th e g ut of wa rm - bl oo d ed an im als . T h e s p or e s c a n
s ur v i ve d is i nf ec ti o n. T he pres e nc e of s p or es i n
dr ink i n g wa ter in d ic at e s h is tor ic c o nt am in a ti o n
th at r eq u ir es i n ves t ig a ti o n. T he s t a nd ar d is
0 p er 10 0m l.
48
Western region
Coa gul at ion
a pr oc es s em p lo ye d d ur in g dr i nk in g wa t er
tre atm e nt t o as s is t wi t h th e rem o va l of
par t ic u l a te m att er.
Col ifo rm b act e ri a
are wi d e l y d is tr i bu t ed i n th e e n v iro nm en t of t en
as a r es u lt of h um an o r a n im al ac t i vi t y, bu t s om e
gro w o n p l an t m at ter . T hei r pres e nc e i n a w at er
s up p l y i n dic a t es a ne e d to in v es ti g at e t he
i nt egr i t y of t h e wa t er s up p l y s ys t em .
T he s ta n dar d is 0 pe r 10 0m l.
Colo n y c ount s
are ge n era l t ec hn i q ue s f or d et ec t i ng a wi d e
ran g e of bac t eri a , th e t yp e s a nd num bers be i ng
de p en d en t o n th e c o n d it i ons of t he t es t .
T hes e c o u n ts , if d on e reg u l ar l y, c a n h e lp t o
i nf orm wa ter m an ag em en t, bu t th e y h a v e no
d irec t h ea l th s ig n if ic a nc e . T h e s t an d ard is ‘ no
ab n orm al c h a ng e ’.
Colo ur
oc c urs na tu ra l l y i n u p l an d wat er s o urc es . I t i s
rem ov e d b y c o n ve nt i o na l wat er tr e atm en t.
A n at i on a l s t a n d ar d of 2 0m g/ l on t h e
P la t in um /C ob a lt ( Pt /C o) s c a le ap p l ies .
Com mun ic at ion pip e
th e c o nn ec ti o n f r om th e wa t er m ai n t o th e
c ons um er’s pro p ert y b ou n da r y.
Comp li an c e a ss e ss m ent
a c om par is on m ad e b y t he I ns pec t ora te of d a ta
ga t her e d b y wa t er c om pa n i es ag a i ns t s t a nd ar ds
an d o th er re g u la to r y r eq u ir em ents .
Comp ound
a c om po un d c o ns is ts of t wo or m ore e l em en ts i n
c hem ic a l c om bi na t io n .
Con ce s sio na r y sup pl ie s
h is t or ic a l f re e s up p l i e s of wa t er f or a
ho us eh o l der , es ta b l is h ed wh en a c om pa n y
wa nt e d to la y m a i ns a c ros s l an d a n d th e
l an d o wne r m ig h t agr e e , s ubj ec t t o a p erm is s i on ,
to t ak e a s u pp l y of wa t er f r om th e m ai n .
Condu ct iv it y
is a n o n - s p ec if ic m eas ure of t he am oun t of
na t ura l d is s o l ve d i n or ga n ic s u bs t a nc es in
s ourc e wat ers . A n i nd i c at or p ar am eter wi th a
gu i d e v a lu e of 2, 5 00 µ S/c m .
Cont ac t t an k
a ta nk , norm a l l y s it u at ed on a tr e atm en t wo r k s
s it e , wh ic h f orm s p ar t of t h e d is i nf ec t io n pr o c es s .
A d is inf ec t a nt c h em ic a l ( n orm al l y c h l or in e) is
dos e d i nt o t he wat er a s i t f lo ws i nt o t he t a nk .
T he pe ri o d of t im e t h a t t h e wa t er tak es t o f lo w
thr o ug h t he t a nk a l lo w s s uf f ic i en t ‘c on t ac t ’ t i m e
f or t h e c hem ic a l to k il l , or d eac t i va te , a n y
v ir us es o r pa t ho g en ic org a n is m s th at m a y b e
pres e nt in t h e wa t er.
49
Drinking water 2010
Cont r av ent ion
a br eac h of a r e gu l at o r y re q u irem en t.
Copp e r
i n dr ink i n g wa ter c om es m os tl y f r om c o pp er
p ip es a nd f i tt i ngs in h ous e ho l ds . I n g e ner a l,
wa ter s ourc es ar e n ot ag gr es s i ve t o war ds
c op p er, b u t pr ob l em s v er y oc c as i o n al l y oc c u r o n
ne w h ous i n g es t at es . T hes e ‘b l u e wa ter ’ e ve nts
c an be a v o i de d b y g o o d p lum b in g pr ac t ic es .
A E ur op e a n he a lt h - b a s ed s t a nd ar d of
2m g/l ap p l ies .
Cr ypt osp or id ium
is a p ar as it e th a t c aus es s e v ere g as tro e nt er i tis
an d c a n s ur v i v e d is inf ec t i on . I n th e U K,
c on t in u ous m on it or i ng is u nd er tak e n at work s
c l as s if ie d b y t h e c om pan y a s be i n g at
s i gn if ic a nt r is k .
C yan id e
is n ot pr es e nt i n dr i nk i ng wa ter . A Eur o pe a n
he a lt h - b as e d s t an d ard of 5 0 μ g/ l a pp l i es .
De ad l eg
r ef ers t o a p i ec e of p i p in g wh ic h is s t o p pe d of f at
on e e n d, b ut is c o nn ec te d t o t h e s u pp l y a t t h e
ot h er en d a n d c a n r es u lt i n s t ag n an t wa t er i n
th e p i pe wo rk .
Di st rib utio n s yst em s
a wa t er c om pa n y’s ne t work of m a ins , p i pes ,
pum p in g s t at i ons an d s er v ic e r es er v o irs t hro ug h
wh ic h tre a te d wat er is c on v e ye d t o c o ns um ers .
Dr in kin g w at e r st a nd ar ds
th e pr es c r ib e d c o nc e n tra t io ns or va l u es l is t e d
i n r eg u l at i ons .
EC D r in kin g W at er D i re ct iv e
Co u nc i l D ir ec t i v e 9 8/ 8 3/ E C Dec em ber 1 9 98 –
s et t in g o ut dr i nk i ng wa ter s t a nd ar ds to be
ap p l ie d i n m em ber s t a tes .
Enfo r c em ent a ct ion
th e m ea ns , as s et ou t i n th e W ater Ac t 1 9 89
an d c o ns ol i d at e d i nt o th e W ater I n dus tr y Ac t
19 9 1, b y wh i c h th e S e c ret ar y of S ta te r eq u ir es
a wa t er c om pa n y to c o m pl y w i t h c e rt a in
r eg u l at or y re q uir em en t s .
Ent e ro co cc i
s ee Es c h er ic h ia c o l i .
Env i ro nm ent Ag en c y
th e E n v ir onm en t A g en c y is r es p o ns ib l e f or
m aint a i n in g or im pr o v i ng t h e q ua l it y of f res h,
m arin e, s urf ac e an d u nd er gr ou n d wa t er i n
E ng l a nd a n d W ales .
50
Western region
Ep ic hlo ro h yd r in
c an be f o un d i n tr ac e am oun ts i n p o l yam i ne
wa ter t re atm e nt c h em ic a ls . Its pres e nc e i n
dr ink i n g wa ter is l im it e d b y c o ntr o l of t h e pr o duc t
s pec if ic a t io n. A E ur op ea n h e al t h - b as ed s t a n dar d
of 0 . 1 μ g/ l a pp l i es .
Ep id em iolo g y
a pr oc es s of s t ud yi n g th e d is tr i b ut i on of c as es of
d is e as e wi t hi n a p o p ul at i on in r e la t io n t o
ex p os ur e t o p os s i bl e s ourc es of th e i nf ec t io n ,
wi t h a v i e w t o es ta b l is h in g t he ac t ua l s o urc e of
th e i nf ec ti o n.
E sc he ri ch i a col i an d
Ent e ro co cc i
are bac te ri a pr es en t i n t he gu t of warm - b lo o d ed
an im a ls . T h e y s h o ul d no t b e pr es e n t i n dr ink i ng
wa ter an d, if p res e nt , i m m edia t e ac t i on is
req u ir ed t o i d en t if y a n d r em ov e a n y s o urc e o f
f aec al c on tam i na t io n t ha t is f o un d. T he s t a n dar d
is 0 p er 1 0 0m l.
Ev e nt
wa ter c om pan i es h a v e t o i nf orm th e I ns p ec to rat e
ab o ut oc c as i ons wh en wa ter qu a l it y or
s uf f ic i e nc y is af f ec t e d or wh e n p ub l ic c o nf i d e nc e
i n dr ink i n g wa ter qu a l i t y m a y b e im pac t e d. T he
Ins p ec t ora t e r ef er t o t hes e i ns ta nc es as ‘ E v en ts ’ .
Filt r ati on
th e s e par a t io n of s us p en d ed par t ic u l at e m att er
f rom a f l u id .
Fluo ri de
oc c urs na tu ra l l y i n m a n y wa t er s ou rc es ,
es p ec i al l y g ro u nd wa t e r. It c a n no t b e r em ov e d b y
c on v e nt i on a l wa t er tr e atm en t s o h i gh le v e ls m us t
be r ed uc ed b y b le n di n g wi t h a no th er lo w f lu o ri de
wa ter s ourc e . S om e wat er c om pa n ies are
req u ir ed b y th e l oc a l h ea l th au th or i t y to
f lu or id at e wat er s u p p li es as a pr ot ec ti o n a ga i ns t
to ot h d ec a y. T he dr i nk i ng wat er s t a nd ar d
ens ur es l e v els are s af e i n e it h er c irc um s tan c e.
Fl uo ri d at i on of wat e r i s a D e par tm ent of H ea lt h
po l ic y. A E ur o pe a n he a lt h - b as e d s ta n dar d of
1. 5m g/ l ap p l i es .
G eo sm in
a s u bs t anc e pr o duc e d b y th e gr o wt h of a l g ae ,
norm a l l y i n s urf ac e wa ters wh ic h g i ves r is e t o a
c har ac ter is t ic ‘ ear t h y’ or ‘m us t y’ t as t e or o d o ur.
G r anu la r a ct iv at ed c a rbon
an ads or be n t f i l tra t io n m edi a us e d to r em ov e
trac e or g an ic c om po u n ds f rom wat er .
G rou ndw at er
wa ter f rom a q uif ers or o th er u n der gr o un d
s ourc es .
51
Drinking water 2010
H yd ro ge n Ion
(pH)
g i ves a n i n d ic a t io n of th e d egr e e of ac id i t y o f th e
wa ter . A pH of 7 is n e utr a l; va l u es b el o w 7 a re
ac id ic a n d v a lu es a b o v e 7 ar e a lk al i n e.
A l o w pH wat er m a y re s u lt i n p i pe c orros i o n.
T his is c orr ec te d b y a dd i n g an alk a l i d ur in g
wa ter t re atm e nt. A s p e c if ic at i o n of b e t wee n 6 .5
an d 9 .5 ap p l ies .
Imp rov em ent pr og ra mm es
wa ter c om pan y im pr o v em ent work s , th es e ar e
l eg a l l y b in d i ng o n t he c om pan y a n d e ac h
pr o gr am m e wi l l r em ed y a n ac tu a l or p ot e nt i a l
br e ac h of a dr ink i n g w at er s t an d ard wi th i n a
s pec if ie d t im e p er i od .
Indi c ato r or ga ni sm
an org a n is m wh ic h i nd ic at es th e pr es enc e of
c on t am in at i on a n d h en c e th e p os s ib l e pr es en c e
of p a th o ge ns .
Indi c ato r pa r am et er
s om eth i n g t h at is m ea s ure d t o c h ec k th a t
c on tr ol m eas ur es , s uc h as wa t er tr ea tm ent , are
work i n g ef f ec t i ve l y.
Info rm at ion Le t t e r
f orm al gu i d anc e t o wa t er c om pa n ies g i v e n b y
th e I ns p ec t or at e a n d p ub l is he d o n t he
Ins p ec t ora t e ’s we bs it e a t ww w. d wi .g o v .uk
Ins pe cto r at e
T he Dr ink i ng W ater I n s pec t ora te .
Iro n
is pr es e n t n at ura l l y i n m an y wa t er s o urc es . I t is
r em ov e d b y wa t er tre a tm ent . S om e i ro n
c om pou n ds ar e us ed a s wat er t r ea tm ent
c hem ic a ls . H o we v er, t he c om m ones t s ou rc e
of iro n i n dr i nk in g wa t er is c orr os i on of ir o n
wa ter m ai ns . A n at i on a l s ta n dar d of
20 0μ g /l ap p l ies .
Le ad
v er y oc c as i o n al l y oc c u rs n at ur a l l y i n r a w wa t ers ,
bu t t he us u a l r e as o n f or i ts pr es e nc e i n dr in k i ng
wa ter is p l um bin g in o l der pro p ert i es . If th e wa ter
s up p l y h as a t en d enc y t o d is s o l v e l e ad t h en
wa ter c om pan i es tr ea t t he wa ter t o re d uc e
c ons um er ex p os ur e. T he perm an e nt r em ed y is
f or h o us e h o ld ers t o r e m ove l e a d p ip es a nd
f itt i n gs . A E uro p ea n h ea l th - b as ed s t a nd ar d of
25 μg / l a pp l i es , b ut 10 μg /l wi l l a pp l y f r om 2 5
Dec em ber 2 0 13 o n war ds .
3
m /d
c ub ic m etre per da y.
M angan es e
is pr es e n t n at ura l l y i n m an y s o urc es a nd is
us u a l l y r em ov e d d ur in g tre a tm ent . A n at i o na l
s ta n dar d of 5 0 μ g/ l a pp l ies .
52
Western region
M ean z on a l com pl ia n ce
pe rc en t ag e
a m eas ur e of c om pl ia n c e wi t h dr i nk in g wa t er
s ta n dar ds i n tro d uc e d b y th e I ns p ec tor at e in
20 0 4.
M ercu r y
is n ot f o un d i n s o urc e s of dr ink i n g wa t er.
A E ur op e a n he a lt h - b a s ed s t a nd ar d of
1μ g/ l a p pl i es .
mg/ l
m ill i gr am per li tr e ( o n e th o us a n dt h of a gr a m
per l itr e).
M icrob iol ogi c al
as s oc i at e d wi t h th e s t ud y of m ic ro bes .
M l/d
m ega l itr e p er d a y ( o ne M l /d is eq u i v a le nt t o
3
1, 0 00 m /d , or t o 22 0 , 00 0 g a l lo n/ d) .
Ni ck e l
oc c urs na tu ra l l y i n s o m e gro u nd wa t er a nd wher e
nec es s ar y s p ec ia l tr e a tm ent c a n b e i ns t a l le d t o
rem ov e i t. An ot h er s o u rc e of nic k e l i n dr i nk in g
wa ter is th e c o at i n gs o n m od er n ta ps a n d ot h er
p lum b in g f it t in gs . A E u rop e a n he a lt h - b as e d
s ta n dar d of 2 0 μ g/ l a pp l ies .
Nit r ate
oc c urs na tu ra l l y i n a l l s ourc e wat ers a l th o ug h
h ig h er c o nc e ntr a ti o ns te n d to oc c ur wh ere
f ert il is ers ar e us e d on th e l a nd . N itr at e c a n b e
rem ov e d b y i on ex c h a ng e wat er tr ea tm en t or
thr o ug h b l en d i ng wi th ot h er l o w n i tra t e s ou rc es .
A E ur op e a n he a lt h - b a s ed s t a nd ar d of
50m g/ l a p p li es .
Nit rit e
is s om et im es p ro d uc e d as a b y - pr od uc t wh e n
c h lor am in e is us e d as th e es s en t ia l r es i d ua l
d is i nf ec ta n t i n a p ub l ic wat er s u pp l y.
Ch l or am ine is th e res i du a l d is inf ec t an t of c h o ic e
i n l arg e d is tri b u t i o ns s ys t em s b ec a us e i t is m or e
s ta b le an d l o ng - l as t i n g. C ar ef u l o per at i o n of t he
d is i nf ec t io n pr oc es s e ns ur es l e v e ls of ni tr it e ar e
k ept b e lo w th e s t an d ar d. A E uro p ea n h e a lt h bas e d s ta n da rd of 0 .5 m g/l a pp l i es .
Noti c e
an ins tr uc t i on s er ve d b y th e S ec r e t ar y of S t at e
(i n th e c as e of wa ter s up p l ies , t he C h ief
Ins p ec t or of W ater) re qu ir i n g s pec if ic ac t i on s t o
be t ak en b y th e r ec i p i en t wi t h in a s pec if ie d
tim es c a l e.
O dou r
c an aris e as a c ons e q ue nc e of na tu ra l pr oc e s s es
i n s urf ac e wa t ers , p ar t ic ul ar l y b et we e n l at e
s pr in g a n d ear l y a u tu m n. W ater tr e atm en t w it h
ac t i v at e d c ar bo n or o z on e wi l l r em ov e n at ur a l
s ubs t anc es c a us in g t a s te . T h e s ta n da rd r el a tes
to t h e e va l u at i ons of a p a ne l of p eo p le as s es s i ng
s am pl es i n th e l a bo ra t or y.
53
Drinking water 2010
O fw at
th e wa t er i n dus tr y’ s ec o n om ic r e gu l at or .
O oc ys t
th e r es is t a nt f orm i n w h ic h Cry pt os p ori d i um
oc c urs in t h e e n v iro nm en t, an d wh ic h is c ap a b le
of c a us i ng inf ec t io n .
O rg ano l ept i c
c har ac ter is t ic s of a s u bs t a nc e as de tec t ed b y o u r
s ens es , f or ex am pl e t a s te , o do ur or c o l o ur.
O z o ne p ro ce s s ( oz on at i on)
th e a pp l ic at i on of o zo ne gas in d ri nk i ng
wa ter t re atm e nt.
P ar am et e rs
th e s u bs t a nc es , or ga n i s m s and p ro p ert i es l is te d
i n Sc he d u le 2 an d R eg u la t io n 3 of th e
r eg u l at i ons . P ar am ete r d ef i n it i o ns c an be f o un d
f urth er o n i n t h is an n e x .
P athog en
an org a n is m wh ic h c a n i nf ec t hum ans an d
c aus e d is eas e .
PC V
s ee ‘ Pres c r i b ed c onc e ntr at i o n or v a l ue ’ .
P er iod i c rev iew
th e ec on om ic r e gu l at o r’s pr oc es s of s e tt i n g
wa ter pr ic es .
P est i cid e s
an y f u ng ic i de , h er bic i d e, ins ec t ic i de or r e la t e d
pr o d uc t ( ex c l u d in g m ed ic i n es ) us ed f or t he
c on tr ol of p es ts or d is eas es .
P est i cid e s – or gan oc hlo rin e
com poun ds ( ald ri n, d ie ld rin ,
hept a chl or , he pt a ch l or
epo xi de)
ar e no lo n ger us e d i n t he U K b ec a us e t h e y ar e
pers is te n t i n th e e n v ir onm en t. T h e y ar e no t f o u n d
i n dr ink i n g wa ter . A E uro p e an c h em ic a l s t a n dar d
of 0 . 03 μg / l f or e ac h c o m poun d a p p li es .
P est i cid e s – ot h er t h an
org ano ch lo ri ne c omp ound s
is a d i v ers e an d l ar g e gro u p of org a n ic
c om pou n ds us ed as w ee d k il l ers , ins ec tic i d e s
an d f un g ic id es . M an y wa ter s o urc es c o nt a i n
tr ac es of on e or m ore pes t ic id es as a r es u l t of
bo t h agr ic u lt ur a l a nd n on - a gr ic u l tu ra l us es ,
m ain l y o n c r o ps an d f o r wee d c o nt ro l o n
h ig h wa ys a n d i n g ard e ns . W here n ee d ed , wa ter
c om pan i es h a v e i ns t a l l ed wat er tr e atm en t
( ac t i v at e d c ar bo n a n d o zo n e) s o t ha t p es t ic i des
ar e no t f o u n d i n dr ink i ng wa ter . W ater c om p an i es
m us t t es t f or th os e p e s tic i d es us e d wi de l y i n
th e ir ar ea of s u p pl y. P es t ic i de m on it or in g t h us
v ar ies ac c or d in g t o r is k . A E ur op e an c hem ic a l
s ta n dar d of 0. 1 μ g /l f or e ac h i nd i v i du a l s u bs t anc e
an d 0 .5 μg / l f o r t h e t ot a l of a l l p es t ic i des ap p l ies .
54
Western region
Pho sp hat e do sin g
tre atm e nt of wa t er th a t r es u l ts i n a pr ot ec ti v e
f ilm b u il d i ng up o n t he i ns i de of p i pes m in im i s i ng
th e l ik e li h oo d of l e ad be i n g pr es e nt in dr ink i ng
wa ter s up p l ie d t hr ou g h l ea d p i pes .
Pl umb oso lv e nc y
th e t en d enc y f or l e ad t o d is s o l v e i n wa t er.
Po l yc yc li c a ro mat i c
h yd ro c ar bon s
(P AH s )
is a gr o up nam e f or s e v era l s u bs ta nc es pr es en t
i n pe tr ol e um - bas ed pr od uc ts s uc h as c oa l t a r.
(s ee B en zo ( a)p yr e n e l i s te d a bo v e f or m or e
i nf orm at io n) . A E ur op e an he a lt h - bas e d
s ta n dar d of 0. 1 μ g /l f or t he s um of a l l th e
s ubs t anc es a pp l i es .
Pow de r ed a ct iv at ed c ar bon
(P AC )
po wd er e d ac t i v at e d c a rbo n is em pl o ye d i n
tre atm e nt pr oc es s es t o r em ov e p o l lu ta n ts .
P re- and po st - re nov a t ion
as s es s men t ( P PR A)
a pr ogr am m e of as s es s m ent bef ore an d af t er
m ains re n o va t io n t o d em ons tr a te j us t if ic at i o n
f or t h e work , a nd t h e i m prov em en ts ac h i e v e d
b y th e re n o va t io n .
P re s c rib ed c onc en t r a t ion o r
v alu e ( P C V)
th e n um eric a l v a lu e as s i gn e d to d ri nk i ng wat er
s ta n dar ds d ef i n in g t he m ax im al or m in im al le ga l
c onc e nt r at i o n or v a l ue of a p aram et er .
P riv ate s upp li e s
wa ter s up p l ie d f or h u m an c o ns um pti o n or f o od
pro d uc t i o n wh ic h is n o t pro v i d ed b y a wa t er
un d ert ak er or l ic e ns e d wat er s u pp l i er.
P rotoz oan p a ra si t e s
a s i ng l e c e l l or ga n is m th at c an o n l y s ur v i v e b y
i nf ec t i ng a hos t.
Pub li c R egi st e r
dr ink i n g wa ter qu a l it y i nf orm at io n m a de a v a i l ab l e
to t h e pu b l ic b y wa t er c om pan i es as re q u ire d
b y r e gu l at i o ns .
Pub li c su ppl i es
wa ter s up p l ie d b y a c o m pan y l ic ens e d f or
th at pur p os e .
Raw w at e r
wa ter pr ior t o rec e i v in g t re a tm ent f or t he p ur pos e
of dr i nk i ng .
Reg ul at i on s
T he W ater S u pp l y (W ater Q ua l it y) Re g ul a ti o n s
20 0 0 ( E n gl a nd ), 2 0 10 (W ales ).
Re me di al a ct ion
ac t i on t ak en t o im pr o v e a s i tu a ti o n.
Re si du al di si nf e ct ant
th e s m a ll am oun t of c h l ori n e or c h l or am in es
pres e nt in dri nk i ng wa ter t o m a in t ai n i ts q ua l it y
as i t pas s es t hro u g h t he wa ter c om p an y’ s
ne t work of p i pes a n d h ous e ho l d p l um bi ng .
55
Drinking water 2010
Ri sk as s es sm ent
a r e v ie w u n der tak e n t o i de n tif y ac tu a l or
po t en t ia l h a za rds t o h um an h ea l th in a wa te r
tr e atm e nt work s a nd a s s oc ia te d s u p pl y s ys t e m .
Pr i ori t is at i on of r is k is b as ed o n c o ns id er at i o n of
l ik el i ho o d a nd c ons e q ue nc e of t h e r is k oc c u rri ng .
S ec r et ar y of St at e
S ec re t ar y of St at e f or E n vi ro nm en t, Fo o d
an d R ur al Af f airs .
S el en ium
is a n es s en t ia l e l em en t an d a n ec es s a r y d ie t ar y
c om pon e nt . Am ou n ts i n dr ink i n g wa t er ar e
us u a l l y we l l b e l o w t he s ta n dar d. A E ur op e an
he a lt h - b as e d s t an d ard of 1 0 μ g/ l a pp l i es .
S erv ic e co nne ct ion
c on n ec t i on be t we en t h e wa t er c om pa n y's m a i n to
a c o ns um er ’s pr op ert y .
S erv ic e pip e
an y p i p e s u bj ec t to m ai ns wa ter pres s ur e or
s ubj ec t t o m ai ns pres s ure bu t f o r th e c l os in g of
s om e va l v e.
S erv ic e r e se rv oi r
a wa t er to we r, t ank or ot h er r es er vo ir us e d f or
th e s t ora g e of tr e at e d wa ter wi th i n t he
d is tr i bu t io n s ys t em .
Sod iu m
is a c om po n en t of c om m on s a l t. I t is pr es en t i n
s ea wa t er a nd brac k is h gr o un d wa ter .
S om e tr ea tm en t c hem i c a ls c on t ai n s o d ium .
Co nc en tr at i ons in d ri n k ing wat er ar e ex tr em e l y
l o w, bu t s om e wa ter s of te n ers c a n a dd
s i gn if ic a nt am o un ts to dr ink i n g wa ter wh er e t he y
ar e ins t a ll e d i n h om es or f ac t or i es . A na t io n a l
s ta n dar d of 2 00m g/ l a pp l i es .
Sp ri ng s
gr o u n d wat er a p pe ar in g at t h e s urf ac e at t h e
ou tc r op of t he j u nc ti o n of a p erm ea bl e s tr at u m
wi t h an im perm ea b le s tra tum .
Su lph at e
oc c urs na tu ra l l y i n a l l wa ters an d is dif f ic u lt to
r em ov e b y tr e atm en t. A n i nd ic at or p ar am ete r wit h
a g ui d e v a lu e of 2 50m g/ l .
Sup pl y pip e
s ee s er vic e p i p e.
Sup pl y poi nt
a p oi n t ot h er th a n a c o ns um er ’s ta p a ut h or is ed
f or t h e tak i ng of s am p l es f or c om pl ia nc e wi t h
th e r e gu l a ti o ns .
Su rf ac e w at e r
un tr ea t e d wat er f rom ri v ers , im p ou n di n g
r es e r vo irs or ot he r s ur f ac e wa t er s o urc e .
56
Western region
T aste
c an aris e as a c ons e q ue nc e of na tu ra l pr oc e s s es
i n s urf ac e wa t ers , p ar t ic ul ar l y b et we e n l at e
s pr in g a n d ear l y a u tu m n. W ater tr e atm en t w it h
ac t i v at e d c ar bo n or o z on e wi l l r e m ov e n at ur a l
s ubs t anc es c a us in g t a s te . T h e s ta n da rd r el a tes
to t h e e va l u at i ons of a p a ne l of p eo p le as s es s i ng
s am pl es i n th e l a bo ra t or y.
T echn ic al aud it
th e m ea ns of c h ec k in g t ha t wa t er c om pa n ies are
c om pl yi n g wi th t h ei r s t at ut or y o b l ig a ti o ns .
T etra ch lo ro et h an e an d
T rich lo ro et h en e
are s ol v e nts t h at m a y oc c ur in gro u nd wa t er i n
th e v ic i n it y of i nd us tr i a l s it es . W here n ec es s ar y
th e y ar e r em o ve d b y s pec i a l is t tr e atm en t.
A E ur op e a n he a lt h - b a s ed s t a nd ar d of 10 μg / l f or
th e s um of bo th s ubs t anc es a p pl i es .
T etra ch lo ro met han e
is a s o l v en t t ha t m a y o c c ur i n gr ou n d wat er in t he
v ic in i t y of in d us tr i a l s i t es . W here n ec es s ar y i t is
rem ov e d b y s p ec i a l is t wa ter t re atm e nt.
A n at i on a l s t an d ar d of 3 μg / l ap p l ies .
T ime of sup pl y
th e m om ent wh en wa t er p as s es f rom th e w a ter
c om pan y’ s pi p e work i n to a c ons um er’s p i p e work .
T otal ind ic at iv e d o se
is a m eas ur e of th e ef f ec t i v e d os e of r a d ia t io n
th e b od y wi l l rec e i ve f rom c ons um pt i on of t h e
wa ter . It is c a lc u l at e d on l y wh e n s c r ee n in g
v a lu es f or gr os s a lp h a or g ros s b e ta (r ad i at i on)
are ex c e e de d . A n i nd i c at or p ar am eter wi th a
gu i d e v a lu e of 0. 1 0m Sv/ ye a r.
T otal o rg an i c c a rb on
rep res e nts t he t o ta l a m ount of or g an ic m att er
pres e nt in wa ter . A n i n d ic a tor par am et er wi t h a
gu i d e v a lu e of ‘ no ab n orm al c h a ng e ’.
T oxic olo g y
th e s t u d y of t he h e a lt h ef f ec ts of s u bs t a nc es .
T reat ed w at e r
wa ter t re at e d f or us e f or d om es tic pur p os es as
def in e d i n th e re g u la t i ons .
T riha lo met ha ne s
are f orm ed d ur i ng d is i nf ec t i o n of wat er b y a
reac t io n b e t wee n c h l or i ne a n d n at ur al l y oc c u rri ng
org a n ic s u b s t anc es . T he ir p ro d uc t i on is
m inim is e d b y g o o d op era t io n a l pr ac t ic e.
A E ur op e a n he a lt h - b a s ed s t a nd ar d of 10 0 μ g /l
ap p l ies .
T ritiu m
is a ra d i oac t i ve is o to p e of h ydr o ge n .
Dis c h ar ges t o t he e n v i ronm e nt ar e s tr ic t l y
c on tr ol l e d a nd t h ere is a n a ti o na l p ro gr am m e of
m onit or i ng s urf ac e wa t ers . An in d ic at or
par am et er wi t h a g u id e v a lu e of 1 00 B q/ l .
57
Drinking water 2010
T urbid it y
is a m eas ur e of th e c l ou d i nes s of wa t er. At
tr e atm e nt work s , m eas urem e nt is an im port a nt
no n- s p ec if ic wa t er q ua l it y c o n tro l p ar am eter
bec a us e it c a n b e m o n it or ed c on t in u ous l y o n l i n e
an d a l arm s s et t o a l ert o p era to rs to d e ter i or a ti o n
i n r a w wat er q u a li t y or t he ne e d to o p tim is e
wa ter t re atm e nt. A n i n d ic a tor par am et er wi t h a
gu i d e v a lu e of 1NT U . W hen d et ec te d a t th e
c ons um er’s t a p i t c an ar is e f rom d is t ur ba nc e of
s ed im en t wi t h in wa ter m ains . A n at i on a l s t an dar d
of 4 NT U ap p l i es i n th i s c as e.
Und er ta ki ng s
l eg a l l y b i n d i ng pr o gr a m m es of work ag re e d
be t we en a wa te r c om pan y a n d t he C h ief
Ins p ec t or of D ri nk i ng W ater t o ad dr es s ac tu a l or
po t en t ia l wat er q u al i t y is s u es .
Vi n yl ch lo rid e
m a y be p res e nt i n p l as tic pi p es as a res i d ua l of
th e m an uf ac tu ri n g pr o c es s of po l yv i n yl c hl or i de
( P VC ) wa ter p ip es . I ts pr es enc e i n dr i nk in g wa ter
is c o ntr o l le d b y pr o d u c t s pec if ic a t io n.
A E ur op e a n he a lt h - b a s ed s t a nd ar d of 0. 5μ g/ l
ap p l ies .
W ate r s upp l y z on e
a pr e- d ef i n ed are a of s up p l y f or es t a b lis h i ng
s am pl i ng f re qu e nc ies , c om pl i anc e wi t h s t an d ards
an d i nf orm at i on t o b e m ade p ub l ic l y a v a il a b l e.
W HO
W orld H e a lt h O r g an is a ti o n.
W hol es om e/w hol e so men e ss
a l eg a l c o nc e p t of w at er q ua l it y wh ic h is d ef i ne d
b y r ef er e nc e t o s t an d a rds a nd o t her
r eq u ir em ents s et o ut i n th e re g u la t io ns .
58
Western region
Annex 3
Drinking water quality events in the region
Not significant and minor drinking water quality ev ents
Nature
Chemical
Number of not significant a nd minor events
3 – BRL (1), W SX (2)
Discolouration
3 – BRL (1), W SX (2)
Health concern
1 – BRL (1)
Loss of
supplies/poor
pressure
7 - BRL (1), CHO (1), SW T (3), W SX (2)
Mi c r o b i o l o g i c a l
1 – BRL (1)
Other
2 – SW T ( 2 )
Public concern
8 – B R L ( 2 ) , SW T ( 1 ) , W S X ( 5 )
Total
25 – BRL (7), CHO (1), SWT (6), WSX (1 1)
Area affected (estimate of population affected)
Te t b u r y, G l o s ( 1 5 )
Ilminster (3)
Burbage (3)
Th o r n b u r y, B r i s t o l ( 3 , 3 5 0 )
Ye o vi l , S o m e r s e t ( 4 , 8 0 0 )
South Petherton and Bower Hinton, Somerset (5 ,500)
L i t t l e t o n W TW ( 1 0 0 , 0 0 0 )
Brent Knoll and East Brent (23,893)
Shipton Bellinger, Hampshire and Cholderton, Wiltshire
(250)
Helston, nr Falmouth (4,000)
W hi t c h u r c h , n e a r Ta vi s t o c k ( 5 , 5 0 0 )
Te i g n m o u t h , D e vo n ( 2 , 0 0 0 )
Bath (17,500)
H o l l y w o o d B o w, T a u n t o n ( 1 2 , 2 1 4 )
Alderley area of Bristol (16,440)
W en d r o n , H e l s t o n , n r F a l m o u t h ( 1 5 , 0 0 0 )
St Austell, Newquay and surrounding area (200,000)
W at e r l i p , S o m e r s e t ( 3 0 )
S o u t h wo o d , E ve r c r e e c h , S h e p t o n Ma l l e t ( 3 )
Ma r s h g a t e a n d s u r r o u n d i n g a r e a s , N o r t h C o r n w a l l ( 1 , 2 5 0 )
W ar m i n s t e r R d , B a t h ( 8 3 0 )
C h a f e ys A ve , W e ym o u t h ( 3 )
L e we l l , D o r s e t ( 3 )
W in t e r b o r n e S t i c k l a n d ( 3 )
Ti m b e r s c o m b e , S o m e r s e t ( 3 )
412,593
59
Drinking water 2010
Significant, serious and major drinking water quality events
Date and
duration
Area
20 Jan 2010
For 1 day
(W S X)
R o c k we l l G r e e n ,
W el l i n g t o n ,
Somerset
Estimate of
population
affected
3,900
Nature and cause of
t h e e ve n t
Main actions and findings from the Inspectorate
i n ve s t i g a t i o n
B r o wn d i s c o l o u r a t i o n
due to mains burst.
W e s s e x W a t e r S e r vi c e s L t d a c t i o n :

Flushed mains.

Sampled affected area.
DWI comments and findings:

C r i t i c a l t h a t t h e p l a n s a v a i l a b l e t o t h e N e t wo r k
Te c h n i c i a n d i d n o t c o r r e l a t e wi t h t h e m a i n s l a yo u t o n
site.

Delay in mains isolation.

Recommended that company ensure asset records are
u p d a t e d i n l i g h t o f t h i s e ve n t .
Risk classification: significant
2 1 Ma y 2 0 1 0
For 1 day
( SW T)
P o r t wo r t h y
r e s e r vo i r
s u p p l yi n g a r e a s
o f P l ym p t o n a n d
P l ym o u t h
3,370
South West Water Ltd action:

Sampled affected area.

C o n d u c t e d e xt e r n a l s i t e i n s p e c t i o n a n d p l a n n e d i n a n
internal inspection.
Microbiological
contamination.
DWI comments and findings:

Inadequate procedures.

Recommended company adopts a risk-based
a p p r o a c h t o i t s s e r vi c e r e s e r vo i r m a i n t e n a n c e a n d
inspection programme.

R e c o m m e n d e d c o m p a n y r e vi e w t h e s a m p l i n g f a c i l i t i e s
a t a l l i t s s e r vi c e r e s e r vo i r s a n d e n s u r e s
r e p r e s e n t a t i ve s a m p l e s .
Risk classification: significant
60
Western region
Date and
duration
Area
10 Jun 2010
F o r 2 d a ys
(BRL)
Bradley Stoke,
Bristol
Estimate of
population
affected
10,140
Nature and cause of
t h e e ve n t
Main actions and findings from the Inspectorate
i n ve s t i g a t i o n
B r o wn d i s c o l o u r a t i o n
due to mains burst.
Bristol Water Plc action:

Flushed mains.

Repaired main.

Sampled affected area.
DWI comments and findings:

S u g g e s t e d f u t u r e wo r k o n t h e n e t wo r k b e r i s k
assessed and mitigation measures put in place.

S u g g e s t e d c o m p a n y r e vi e ws r e s p o n s e t i m e f o r
s a m p l i n g d u r i n g a n e ve n t .
Risk classification: significant
02 Jul 2010
For 1 day
( BW H )
A l d e r n e y wo r k s
s u p p l yi n g a r e a s
of Bournemouth
88,000
Bournemouth and West Hampshire Water action:

Collected samples.

Found sample line had additional connections to
equipment presenting a potential backflow risk and is
against company policy.
Mi c r o b i o l o g i c a l
contamination.
DWI comments and findings:

I n a d e q u a t e i n ve s t i g a t i o n s i n t o r o o t c a u s e a n d f a i l e d
t o l i n k f a i l u r e s i n zo n e s t o a k n o wn r i s k a t t h e w o r k s
which had not been mitigated.

Th e I n s p e c t o r a t e i n i t i a t e d e n f o r c e m e n t a c t i o n a n d
m a d e a s i t e vi s i t .

F i l t e r e d wa t e r w a s a l l o w e d t o b yp a s s d i s i n f e c t i o n d u e
t o a d e s i g n f a u l t w h e r e t r e a t e d wa t e r r e s e r vo i r
l o c a t e d u n d e r s l o w s a n d f i l t e r s a n d s e a l s o n ve n t s
created an inherent hazard.

Company have entered into a legally binding
programme of work to remedy the faults .
Risk classification: significant
61
Drinking water 2010
Date and
duration
Area
05 Jul 2010
For 15 hours
( SW T)
E xm o u t h , D e vo n
Estimate of
population
affected
250
Nature and cause of
t h e e ve n t
Main actions and findings from the Inspectorate
i n ve s t i g a t i o n
B r o wn d i s c o l o u r a t i o n
due to mains burst.
South West Water Ltd action:

Collected samples.

P r o vi d e d a l t e r n a t i ve s u p p l i e s , b o ws e r s a n d o ve r l a n d
riders.
DWI comments and findings:

Th e I n s p e c t o r a t e w a s s a t i s f i e d wi t h t h e c o m p a n y ’ s
h a n d l i n g o f t h i s e ve n t .
Risk classification: significant
08 Jul 2010
For 1 day
(W S X)
East Grimstead,
W il t s h i r e
3
Mi s c o n n e c t i o n o f a
p r o p e r t y t o a s e we r .
W e s s e x W a t e r S e r vi c e s L t d a c t i o n :

Mi s c o n n e c t e d a p r o p e r t y t o a s e we r .

Flushed and chlorinated the main and plumbing
s ys t e m .

S a m p l e d p r o p e r t y e xt e n s i ve l y a n d t h e a r e a a s a
precaution.
DWI comments and findings:

Critical of asset records for clean and wa ste water
pipes.

Critical of procedures for new mains connections .

I n ve s t i g a t i o n o n g o i n g .
Risk classification: serious
(see the Drinking water quality events section)
62
Western region
Date and
duration
Area
25 Jul 2010
F o r 3 d a ys
( SW T)
Killiganoon
s e r vi c e
r e s e r vo i r
s u p p l yi n g a r e a s
o f Tr u r o
Estimate of
population
affected
1,600
Nature and cause of
t h e e ve n t
Main actions and findings from the Inspectorate
i n ve s t i g a t i o n
Microbiological
contamination.
South West Water Ltd action:

R e m o ve d s e r vi c e r e s e r v o i r f r o m s u p p l y.

I n c r e a s e d c h l o r i n e r e s i d u a l s a t s e r vi c e r e s e r vo i r .
DWI comments and findings:

C o l i f o r m d e t e c t i o n a t s e r vi c e r e s e r vo i r wa s f o l l o w e d
b y r e p e a t e d d e t e c t i o n s a t r e s e r vo i r a n d i n zo n e
d o wn s t r e a m .

Ingress points in reservoir roof were identified and
repaired.
Risk classification: significant
10 Aug 2010
For 1 day
( SW T)
C r o wn h i l l wo r k s
s u p p l yi n g a r e a s
north of
P l ym o u t h
250,035
South West Water Ltd action:

Sampled affected area.

Identified potential ingress to the contact tank.
Microbiological
contamination.
DWI comments and findings:

I n a d e q u a t e i n ve s t i g a t i o n s i n t o r o o t c a u s e .

Critical of the time taken to highlight potential leaks
in contact tank on site.

Critical of time taken to internally inspect the contact
tank.
Risk classification: significant
63
Drinking water 2010
Date and
duration
Area
10 Aug 2010
F o r 3 d a ys
(W S X)
Small part of
W il t s h i r e
Estimate of
population
affected
15
Nature and cause of
t h e e ve n t
Main actions and findings from the Inspectorate
i n ve s t i g a t i o n
Pesticide (2,4-D).
W e s s e x W a t e r S e r vi c e s L t d a c t i o n :

Flushed mains.

R e z o n e d a r e a ( b r o u g h t i n wa t e r f r o m d i f f e r e n t
source).

Sampled affected area.

Confirmed there was no risk to public health.
DWI comments and findings:

U n a b l e t o c o n c l u d e t h a t t h e s e c o n t r a ve n t i o n s w i l l n o t
recur so initiated enforcement.

A c k n o wl e d g e m e n t o f g o o d j o i n t wo r k i n g b e t we e n t h e
c o m p a n y a n d E n vi r o n m e n t a l H e a l t h .
Risk classification: significant
(see the Drinking water quality events section)
26 Aug 2010
F o r 3 d a ys
( SW T)
Landscore
r e s e r vo i r
s u p p l yi n g
Te i g n m o u t h ,
D e vo n
1,000
South West Water Ltd action:

I n c r e a s e d c h l o r i n e r e s i d u a l s a t s e r vi c e r e s e r vo i r .

R e m o ve d s e r vi c e r e s e r v o i r f r o m s u p p l y.

Sampled affected area.
Microbiological
contamination.
DWI comments and findings:

S e r vi c e r e s e r vo i r r e m a i n s o u t o f s u p p l y .
Risk classification: significant
07 Sep 2010
For 37 hours
( SW T)
P r e wl e y w o r k s
s u p p l yi n g a r e a s
in and around
Okehampton,
D e vo n
4,800
South West Water Ltd action:

S a m p l e d t r e a t m e n t wo r k s .

R e vi e w e d s i t e a l a r m s .
Tu r b i d i t y .
DWI comments and findings:

Critical of the company for its slow respo nse to the
coagulation problems.

R e c o m m e n d e d t h e c o m p a n y r e vi e w s i t s p r o c e s s e s f o r
m a k i n g s t a f f a wa r e o f t h e o p e r a t i o n a l s t a t u s o f w o r k s .
Risk classification: significant
64
Western region
Date and
duration
Area
19 Sep 2010
For 12 hours
(W S X)
C o r f e Mu l l e n ,
Dorset
Estimate of
population
affected
12,700
Nature and cause of
t h e e ve n t
Main actions and findings from the Inspectorate
i n ve s t i g a t i o n
B r o wn d i s c o l o u r a t i o n
due to mains burst.
W e s s e x W a t e r S e r vi c e s L t d a c t i o n :

P r o vi d e d b o t t l e d wa t e r o n r e q u e s t .

Repaired main.

Sampled affected area.

Flushed mains.
DWI comments and findings:

DW I wa s s a t i s f i e d wi t h t h e c o m p a n y’ s h a n d l i n g o f t h i s
e ve n t .
Risk classification: significant
28 Oct 2010
For 13 hours
(BRL)
Street,
Somerset
6,201
Loss of supplies due
to mains burst.
Bristol Water Plc action:

R e zo n e d a r e a ( b r o u g h t i n wa t e r f r o m d i f f e r e n t
source).

Repaired main.
DWI comments and findings:

Th e I n s p e c t o r a t e w a s s a t i s f i e d wi t h t h e c o m p a n y ’ s
h a n d l i n g o f t h i s e ve n t .
Risk classification: significant
06 Dec 2010
F o r 2 d a ys
( SW T)
C r o wn h i l l wo r k s
s u p p l yi n g a r e a s
north of
P l ym o u t h
250,035
South West Water Ltd action:

Replaced faulty equipment.

I n ve s t i g a t e d o p e r a t i o n a n d p e r f o r m a n c e o f t r e a t m e n t
works.
Cryptosporidium.
DWI comments and findings:

DW I wa s s a t i s f i e d wi t h t h e c o m p a n y’ s h a n d l i n g o f t h i s
e ve n t .
Risk classification: significant
65
Drinking water 2010
Date and
duration
Area
23 Dec 2010
For 8 months
(W S X)
N/A
Estimate of
population
affected
N/A
Nature and cause of
t h e e ve n t
Main actions and findings from the Inspectorate
i n ve s t i g a t i o n
Laboratory anomaly
regarding
organochlorine
p e s t i c i d e a n a l ys i s .
W e s s e x W a t e r S e r vi c e s L t d a c t i o n :

R e vi e w o f p r o c e d u r e s .
DWI comments and findings:

Inadequate procedures.

I n a d e q u a t e i n ve s t i g a t i o n s i n t o r o o t c a u s e .
Risk classification: significant
29 Dec 2010
F o r 3 d a ys
( SW T)
E xe t e r a n d E a s t
D e vo n
25,000
South West Water Ltd action:

Collected samples.

Daily company status reports .

Me d i a i n t e r vi e ws .

Ta n k e r s f o r a l t e r n a t i ve s u p p l i e s .
Loss of supplies
causing press
interest.
DWI comments and findings:

DW I wa s s a t i s f i e d wi t h t h e c o m p a n y’ s h a n d l i n g o f t h i s
e ve n t .
Risk classification: significant
29 Dec 2010
For 1 day
(W S X)
Ta u n t o n ,
Somerset
16,900
B r o wn d i s c o l o u r a t i o n
due to mains burst.
W e s s e x W a t e r S e r vi c e s L t d a c t i o n :

Supplied bottled water.

Flushed mains.

R e zo n e d a r e a .

Collected samples.
DWI comments and findings:

Th e I n s p e c t o r a t e w a s s a t i s f i e d wi t h t h e c o m p a n y ’ s
h a n d l i n g o f t h i s e ve n t .

R e s u l t s o f f u r t h e r i n ve s t i g a t i ve s a m p l i n g w e r e
s a t i s f a c t o r y a n d s h o we d t h a t c o m p a n y a c t i o n s w e r e
e f f e c t i ve i n r e t u r n i n g s u p p l i e s t o n o r m a l i n a t i m e l y
manner.
Risk classification: significant
66
Western region
Event affecting a number of water companies
Date and
duration
02 Jul 2010
Duration not
applicable
( S e ve r n
Tr e n t
S e r vi c e s )
Nature and cause of
e ve n t
A n a l yt i c a l
malpractice.
M a i n a c t i o n s a n d f i n d i n g s f r o m t h e I n s p e c t o r a t e i n ve s t i g a t i o n
DWI comments and findings :

S e r i o u s d e f i c i e n c i e s we r e f o u n d b y t h e w a t e r u n d e r t a k e r s o r t h e c o m b i n e d l i c e n s e e s f o r
f a i l i n g t o m e e t t h e i r o b l i g a t i o n s u n d e r R e g u l a t i o n s 1 6 a n d 3 4 f o r a n a l ys i s o f wa t e r
s a m p l e s a n d , i n p a r t i c u l a r , d e r i ve d a n a l yt i c a l d a t a , c o m p e t e n c y, r e t e n t i o n o f a p p r o p r i a t e
r e c o r d s , a n d f o r t h e a p p r o p r i a t e t i m e , u s i n g s u i t a b l e e q u i p m e n t f o u n d i n a n a l yt i c a l
p r a c t i c e s f o r i n o r g a n i c c h e m i c a l a n a l ys i s ( R e g u l a t i o n 1 6 ) .

Full details in the published audit report.

I n i t i a t e d e n f o r c e m e n t a c t i o n i n r e l a t i o n t o t h e e i g h t wa t e r c o m p a n i e s u s i n g S e v e r n T r e n t
S e r vi c e s .
Risk classification: serious
No te : A c om p le t e ta b l e of e ve nts in En g l an d a n d W ales in 2 0 10 c a n b e f o u nd o n t he C D i n th e f o ld er.
It is n am ed Sig nif ic an t d rin ki ng w at e r ev e n ts in E ngl an d and W a le s 2 01 0 .pdf . It is als o a v ai l a bl e o n t he DW I webs i te
( www. d wi .g o v .uk ) .
67
Drinking water 2010
Annex 4
Planned drinking water quality improvements
Company
Parameter,
h a z a r d o r d r i ve r
Site
Due for
Completion
Status
Legal
Instrument
BRL
Cryptosporidium
Cheddar
31-Dec-13
Ongoing
Notice
BRL
Cryptosporidium
Littleton
31-Dec-12
Ongoing
Notice
BRL
Cryptosporidium
Purton
31-Dec-11
Ongoing
Notice
BRL
Cryptosporidium
S h i p t o n Mo yn e
31-Dec-12
Ongoing
Notice
BRL
Cryptosporidium
S t o we y
31-Dec-13
Ongoing
Notice
BRL
Iron
Barrow
3 1 - Ma r - 1 0
Completed
8 - Ma r - 1 0
Undertaking
BRL
Iron
3 1 - Ma r - 1 5
Ongoing
Undertaking
BRL
Iron and
Ma n g a n e s e
3 1 - Ma r - 1 0
Completed
3 1 - Ma r - 1 0
Undertaking
BRL
Iron and
Ma n g a n e s e
Tr u n k m a i n s
rehabilitation
D i s t r i b u t i o n s ys t e m ,
installation of
washouts and mains
flushing
Tr u n k m a i n s c l e a n i n g
pilot study
3 1 - Ma r - 1 0
Completed
3 1 - Ma r - 1 0
Undertaking
BRL
Lead
Sherborne
31-Jul-13
Ongoing
Notice
BRL
Me t a l d e h yd e
B a n we l l c a t c h m e n t
3 1 - Ma r - 1 5
Ongoing
Undertaking
BRL
Me t a l d e h yd e
Littleton and Purton
catchments
3 1 - Ma r - 1 5
Ongoing
Undertaking
BRL
Me t a l d e h yd e
S t o we y c a t c h m e n t
3 1 - Ma r - 1 5
Ongoing
Undertaking
BRL
Nitrate
Frome
04-Sep-14
Ongoing
Undertaking
Littleton
31-Dec-11
Ongoing
Undertaking
Alderney
TBC
Pending
Undertaking
W oo d g r e e n
31-Dec-11
Ongoing
Notice
D i s t r i b u t i o n s ys t e m
3 1 - Ma r - 1 5
Ongoing
Undertaking
B o ve y C r o s s
3 1 - Ma r - 1 2
Ongoing
Notice
Greatwell
31-Dec-11
Ongoing
Undertaking
Ongoing
Undertaking
BRL
BW H
BW H
BW H
SW T
SW T
To t a l
Tr i h a l o m e t h a n e s
Coliform
bacteria, E.coli
Cryptosporidium
I r o n , Tu r b i d i t y
a n d P o l yc yc l i c
aromatic
h yd r o c a r b o n s
Cryptosporidium,
Colour and
Tu r b i d i t y
Iron and
Tu r b i d i t y
SW T
Lead
Drift, Restormel
Central, Dotton and
P yn e s C e n t r a l
3 1 - Ma r - 1 5
SW T
Ma n g a n e s e
A vo n
01-Apr-10
SW T
Ma n g a n e s e
L o we r m o o r
3 1 - Ma r - 1 0
SW T
Ma n g a n e s e
To t t i f o r d
3 1 - Ma r - 1 2
Ongoing
Undertaking
SW T
Ma n g a n e s e
Venford
01-Oct-11
Ongoing
Undertaking
SW T
Pesticides
Drift
3 1 - Ma r - 1 2
Ongoing
Undertaking
SW T
Pesticides
Restormel
3 1 - Ma r - 1 4
Ongoing
Undertaking
68
Sign-off
D e l a ye d
Completed
3 1 - Ma r - 1 0
Undertaking
Undertaking
Western region
Company
SW T
SW T
SW T
WSX
WSX
WSX
WSX
WSX
WSX
WSX
WSX
WSX
Parameter,
h a z a r d o r d r i ve r
Ta s t e , o d o u r a n d
Ma n g a n e s e
Ta s t e , o d o u r a n d
Ma n g a n e s e
To t a l
Tr i h a l o m e t h a n e s
2,4-D
Chlortoluron,
Isoproturon,
MC P A , MC P B ,
2,4-D and
Me t a za c h l o r
Coliform
bacteria
Coliform
bacteria
Coliform
bacteria
Coliform
bacteria
Coliform
bacteria
Contamination
from catchment
Contamination
from catchment
Site
Due for
Completion
Status
Legal
Instrument
Stithians
3 1 - Ma r - 1 0
D e l a ye d
Undertaking
Ta m a r
01-Apr-08
Sign-off
D e l a ye d
Undertaking
W en d r o n
31-Dec-14
Ongoing
Undertaking
F o va n t
TBC
Pending
Undertaking
Friar W addon
31-Jan-11
D e l a ye d
Undertaking
Adber
3 1 - Ma r - 1 1
Completed
3 1 - Ma r - 1 1
Notice
Bathford
3 1 - Ma r - 1 3
Ongoing
Notice
Feltham
3 0 - Ma r - 1 1
Completed
3 1 - Ma r - 1 1
Notice
Mo o r b r a k e C a m p
3 1 - Ma r - 1 3
Ongoing
Notice
S i g we l l s
3 1 - Ma r - 1 3
Ongoing
Notice
B r i xt o n D e ve r i l l
3 1 - Ma r - 1 0
D e l a ye d
Notice
Portesham
30-Sep-10
D e l a ye d
Notice
WSX
Cryptosporidium
D e wl i s h
3 1 - Ma r - 1 2
Ongoing
Notice
WSX
Cryptosporidium
Dunkerton
3 1 - Ma r - 1 3
Ongoing
Notice
WSX
Cryptosporidium
Ta t w o r t h
3 1 - Ma r - 1 3
Ongoing
Notice
WSX
Cryptosporidium
To l l e r d o wn
3 1 - Ma r - 1 4
Ongoing
Notice
WSX
Cryptosporidium
Upton Scudamore
Comb
3 1 - Ma r - 1 2
Ongoing
Notice
WSX
Cryptosporidium
W id d e n h a m
3 1 - Ma r - 1 4
Ongoing
Notice
WSX
E.coli
Grange
3 1 - Ma r - 1 2
Ongoing
Notice
WSX
E.coli
G r o ve N e w
3 1 - Ma r - 1 3
Ongoing
Notice
WSX
E.coli
Tu c k i n g Mi l l
N/A
Ongoing
Notice
WSX
E.coli
Zeals
3 1 - Ma r - 1 3
Ongoing
Notice
WSX
Iron
Danesborough
30-Jun-11
D e l a ye d
Undertaking
I r o n , Ma n g a n e s e
and Turbidity
Isoproturon,
Pesticides,
Me c o p r o p ,
Chlortoluron and
taste and odour
Tr u n k m a i n s
r e n o va t i o n
3 1 - Ma r - 1 5
Ongoing
Undertaking
Sutton Bingham
3 1 - Ma r - 1 4
Ongoing
Undertaking
WSX
Lead
D i s t r i b u t i o n s ys t e m
3 1 - Ma r - 1 5
Ongoing
Undertaking
WSX
Me t a l d e h yd e
Durleigh catchment
3 1 - Ma r - 1 5
Ongoing
Undertaking
WSX
WSX
69
Drinking water 2010
Parameter,
h a z a r d o r d r i ve r
Site
Due for
Completion
Status
Legal
Instrument
WSX
Nitrate
Dunkerton, Chirton,
Fonthill Bishop,
Sturminster
Ma r s h a l l / S h a p wi c k ,
Hooke, Bulbridge and
W yl ye
3 1 - Ma r - 1 8
Ongoing
Undertaking
WSX
Ta s t e a n d o d o u r
Blashford
3 1 - Ma r - 1 4
D e l a ye d
Undertaking
Company
70
Western region
Annex 5
Competition in the water industry
The f ollowing table indicates the ext ent of co mpetition in the water
industr y in England and W ales .
Inset appointments in place in 20 10
Sit e
Ap po int ee
S ho tt o n P ap er ,
S ho tt o n
B ux t ed C h ic k en ,
Fl ix t o n
A lb i o n W ater
W yn yar d , ne ar
W olvis t on
Br ook l a nds , M i lt o n
K e yn es
G re at Bi l l i n g W a y,
Nor th am pt on
Lo n g Cr of t R o a d,
Cor b y
Pr i ors Ha l l , Cor b y
Har t le p oo l W ater
K in gs Cr os s , Lo n do n
T he Br i dg e, Dar tf or d
Me d i a C it y, S alf or d
Q u a ys
G ra yl i n g we l l,
Ch ic hes t er
St atu s
V eo l i a W ater
Ce ntr a l
Inc umb ent and
re gio n
D ŵr C ym r u,
W ales
Es s ex an d S uf f o lk
W ater,
E as t er n r eg i o n
Nor th um br ia n W ater,
Nor th er n r e g io n
A ng l i an W ater,
E as t er n r eg i o n
A ng l i an W ater,
E as t er n r eg i o n
A ng l i an W ater,
E as t er n r eg i o n
A ng l i an W ater,
E as t er n r eg i o n
T ham es W ater,
T ham es re g i on
T ham es W ater,
T ham es re g i on
Un i te d Ut i l it i es ,
Nor th er n r e g io n
P orts m ou th
W ater/S o ut h ern W ater,
S ou th er n r e g io n
T ham es W ater,
T ham es re g i on
T ham es W ater,
T ham es re g i on
T ham es W ater,
T ham es re g i on
T ham es W ater,
T ham es re g i on
W es s ex W ater,
W es tern r e gi o n
A ng l i an W ater,
E as t er n r eg i o n
V eo l i a W ater
Pr oj ec ts
W es s ex W ater,
W es tern r e gi o n
S up p l yi n g
wa ter
A ng l i an W ater
In d ep e nd e nt W ater
Ne t wor k s L td
In d ep e nd e nt W ater
Ne t wor k s L td
In d ep e nd e nt W ater
Ne t wor k s L td
In d ep e nd e nt W ater
Ne t wor k s L td
In d ep e nd e nt W ater
Ne t wor k s L td
In d ep e nd e nt W ater
Ne t wor k s L td
P ee l W ater
Ne t wor k s L td
S S E W ater
Br om le y C om m on,
Br om le y
Ha l e V i l la g e,
T ott en h am
K en n et Is l an d ,
Re a di n g
P ark V i e ws , E ps om
S S E W ater
T he P or t wa y, n e ar
S al is b ur y
Fa irf i e ld P ar k an d
Lo we r W ilbur y F ar m ,
Ar l es e y
Mo D T id wo r t h n ear
A nd o v er
S S E W ater
S S E W ater
S S E W ater
S S E W ater
71
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
S up p l yi n g
wa ter
Drinking water 2010
New inset appointments in place for 2010 (by 31 Ma y 2011)
Sit e
Ap po int ee
B err yf i e lds ,
A yl es b ur y
L la n i li d Par k ,
S ou th W ales
G re at W es ter n
P ark , D i dc o t
K in gs m er e ,
B ic es t er
In d ep e nd e nt W ater
Ne t wor k s L td
S S E W ater
S S E W ater
S S E W ater
Inc umb ent and
re gio n
T ham es W ater,
T ham es re g i on
D ŵr C ym r u,
W ales
T ham es W ater,
T ham es re g i on
T ham es W ater,
T ham es re g i on
St atu s
S up p l yi n g wat er
f rom Apr i l 2 01 1
A pp o i ntm en t
gra n te d
S up p l yi n g wat er
f rom Apr i l 2 01 1
A pp o i ntm en t
gra n te d
Water suppl y licenses in place in 2010
Na me of c omp an y
Dat e li c en se
gr ant ed b y O fw at
1 Dec em ber 0 5
St atu s
A qu a v it a e
Lic en s e
t yp e
Com bi n e d
A v on Va l l e y W ater
Re ta i l
6 A ug us t 10
No t ye t op er at i ng
B us i n es s S tr eam
Re ta i l
23 J an u ar y 0 9
No t ye t op er at i ng
O s pr e y W ater
S er v ic es L t d
S at ec Lt d
Com bi n e d
5 J a nu ar y 0 7
No t ye t op er at i ng
Com bi n e d
24 Ma y 0 6
No t ye t op er at i ng
S e ver n T r en t W ater
S el ec t Lt d
UU W ater S al es L td
Com bi n e d
1 Dec em ber 0 5
Com bi n e d
3 J a nu ar y 0 7
O n e r et a i l c us t om er
E as t er n r eg i o n
No t ye t op er at i ng
W aterc al l L t d
Com bi n e d
1 Dec em ber 0 5
In ac t i v e
Yo rW ater Lt d
Re ta i l
21 Marc h 0 6
No t ye t op er at i ng
72
L ic e nc e r e v ok ed
Western region
Annex 6
Water company indices
Bristol Water plc
Water suppl y arrangements
Comp an y a s set s
Num ber of tr e atm en t w or k s
17
Num ber of s er v ic e r es er vo ir s
16 8
Num ber of wat er s u p pl y zo n e s
52
Le n gt h of m ai ns p i pe ( k m )
6, 6 63
Pop ul at i on s erv ed
P op u l at i on s u p p li e d
1, 1 36 ,0 0 0
Num ber of l oc a l au t ho r it i es
9
W ate r s upp li ed
W ater s u pp l i e d
30 9
( M l/ d a y)
P erc e n ta g e f rom
82
s urf ac e s ou rc es
P erc e n ta g e f rom
12
gro u n d s ourc es
P erc e n ta g e f rom
6
m ix ed s o urc es
Ar e a of supp l y
G lou ce st e rs hi r e, W i lt shi r e, B r is t ol ,
So me r se t
Drinking w ater qualit y summar y data
O v er al l dr in ki ng w at e r q ua lit y*
W ate r t re at m ent
Pr oc es s C o ntr o l I nd ex
Dis i nf ec ti o n In d ex
Di st rib ut io n s yst em s
Dis tr ib u t io n M a in t en a n c e In d ex
Res er v o ir In te gr i t y In d ex
Bui ldi ng w at e r s yst e m s
P aram et er s i nf l u enc e d b y d om es t ic
wa ter s ys t em s
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
99 . 97 %
99 . 97 %
99 . 96 %
Indu st r y av e ra ge
20 1 0
99 . 96 %
99 . 99 %
99 . 98 %
10 0%
10 0%
99 . 86 %
99 . 97 %
99 . 99 %
99 . 97 %
99 . 82 %
99 . 97 %
99 . 88 %
99 . 97 %
99 . 89 %
99 . 99 %
99 . 86 %
99 . 96 %
99 . 92 %
99 . 85 %
99 . 96 %
99 . 89 %
Consumer contacts
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
Indu st r y av e ra ge
20 1 0
Info rm ing c on sum e rs
T ota l n um ber
1, 0 15
1, 0 48
1, 0 28
N/ A
Ra te per 1 , 00 0 p o pu l a ti o n
0. 9 3
0. 9 4
0. 9 0
1. 2 6
Ac c e pt abi lit y of w at e r t o
con su me r s
T ota l n um ber
4, 3 73
2, 9 17
2, 9 35
N/ A
Ra te per 1 , 00 0 p o pu l a ti o n
4. 0 0
2. 6 3
2. 5 8
1. 9 8
Comp l aint s t o t he D r i nki ng W at e r In spe cto ra te
A t ot a l of 2 c ons um er s of Br is t o l W ater plc d i rec t l y c o nt ac te d DW I i n 2 01 0.
Note: Summary results for each company of tests for individual parameters are supplied on
t h e DW I we b s i t e a t w w w . d w i . g o v . u k
* O v e r a l l d r i n k i n g wa t e r q u a l i t y a s r e p r e s e n t e d b y m e a n z o n a l c o m p l i a n c e f o r 3 9
parameters.
73
Drinking water 2010
Bournemouth and West Hampshire Water plc
Water suppl y arrangements
Comp an y a s set s
Num ber of tr e atm en t w or k s
9
Num ber of s er v ic e r es er vo ir s
20
Num ber of wat er s u p pl y zo n e s
10
Le n gt h of m ai ns p i pe ( k m )
2, 7 92
Pop ul at i on s erv ed
P op u l at i on s u p p li e d
42 6 ,0 0 0
Num ber of l oc a l au t ho r it i es
6
W ate r s upp li ed
W ater s u pp l i e d
13 3
( M l/ d a y)
P erc e n ta g e f rom
85
s urf ac e s ou rc es
P erc e n ta g e f rom
15
gro u n d s ourc es
P erc e n ta g e f rom
0
m ix ed s o urc es
Ar e a of supp l y
P art s of Do r set , H am psh ir e a nd
W ilt shi r e
Drinking w ater qualit y summar y data
O v er al l dr in ki ng w at e r q ua lit y*
W ate r t re at m ent
Pr oc es s C o ntr o l I nd ex
Dis i nf ec ti o n In d e x
Di st rib ut io n s yst em s
Dis tr ib u t io n M a in t en a n c e In d ex
Res er v o ir In te gr i t y In d ex
Bui ldi ng w at e r s yst e ms
P aram et er s i nf l u enc e d b y d om es t ic
wa ter s ys t em s
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
99 . 92 %
99 . 99 %
99 . 94 %
Indu st r y av e ra ge
20 1 0
99 . 96 %
99 . 97 %
99 . 72 %
99 . 99 %
99 . 90 %
10 0%
99 . 87 %
99 . 99 %
99 . 97 %
10 0%
99 . 95 %
10 0%
99 . 95 %
10 0%
10 0%
99 . 86 %
99 . 96 %
99 . 85 %
99 . 96 %
99 . 73 %
99 . 89 %
Consumer contacts
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
Info rm ing c on sum e rs
T ota l n um ber
18 4
26 3
Ra te per 1 , 00 0 p o pu l a ti o n
0. 4 3
0. 6 2
Ac c e pt abi lit y of w at e r t o
con su me r s
T ota l n um ber
39 7
57 0
Ra te per 1 , 00 0 p o pu l a ti o n
0. 9 3
1. 3 4
Comp l aint s t o t he D r i nki ng W at e r In spe cto ra te
No c o ns um er s of B o ur nem ou t h a nd W es t H a m ps hir e W ater
i n 20 1 0.
Indu st r y av e ra ge
20 1 0
29 2
0. 6 8
N/ A
1. 2 6
50 5
1. 1 8
N/ A
1. 9 8
p lc d ir e c tl y c on tac t ed DW I
Note: Summary results for each company of tests for individual para meters are supplied on
t h e DW I we b s i t e a t w w w . d w i . g o v . u k
* O v e r a l l d r i n k i n g wa t e r q u a l i t y a s r e p r e s e n t e d b y m e a n z o n a l c o m p l i a n c e f o r 3 9 p a r a m e t e r s .
74
Western region
Cholderton and District Water Company Ltd
Water suppl y arrangements
Comp an y a s set s
Num ber of tr e atm en t w or k s
1
Num ber of s er v ic e r es er vo ir s
1
Num ber of wat er s u p pl y zo n e s
1
Le n gt h of m ai ns p i pe ( k m )
30
W ate r s upp li ed
W ater s u pp l i e d
2
( M l/ d a y)
P erc e n ta g e f rom
0
s urf ac e s ou rc es
P erc e n ta g e f rom
10 0
gro u n d s ourc es
P erc e n ta g e f rom
0
m ix ed s o urc es
Ar e a of supp l y
Sm a ll pa rt s of W ilt sh ir e an d
Ha mp shi r e
Pop ul at i on s erv ed
P op u l at i on s u p p li e d
3, 0 00
Num ber of l oc a l au t ho r it i es
2
Drinking w ater qualit y summar y data
O v er al l dr in ki ng w at e r q ua lit y*
W ate r t re at m ent
Pr oc es s C o ntr o l I nd ex
Dis i nf ec ti o n In d ex
Di st rib ut io n s yst em s
Dis tr ib u t io n M a in t en a n c e In d ex
Res er v o ir In t e gr i t y In d ex
Bui ldi ng w at e r s yst e ms
P aram et er s i nf l u enc e d b y d om es t ic
wa ter s ys t em s
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
10 0%
10 0%
10 0%
Indu st r y av e ra ge
20 1 0
99 . 96 %
10 0%
10 0%
10 0%
10 0%
10 0%
99 . 36 %
99 . 99 %
99 . 97 %
10 0%
10 0%
10 0%
10 0%
10 0%
10 0%
99 . 86 %
99 . 96 %
10 0%
10 0%
10 0%
99 . 89 %
Consumer contacts
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
Indu st r y av e ra ge
20 1 0
Info rm ing c on sum e rs
T ota l n um ber
0
0
0
N/ A
Ra te per 1 , 00 0 p o pu l a ti o n
0
0
0
1. 2 6
Ac c e pt abi lit y of w at e r t o
con su me r s
T ota l n um ber
0
0
0
N/ A
Ra te per 1 , 00 0 p o pu l a ti o n
0
0
0
1. 9 8
Comp l aint s t o t he D r i nki ng W at e r In spe cto ra te
No c o ns um er s of C ho l der t on a n d D is tr ic t W ater C om pa n y Lt d d ir ec tl y c on tac t ed DW I
i n 20 1 0.
Note: Summary results for each company of tests for individual parameters are supplied on
t h e DW I we b s i t e a t w w w . d w i . g o v . u k
* O v e r a l l d r i n k i n g wa t e r q u a l i t y a s r e p r e s e n t e d b y m e a n z o n a l c o m p l i a n c e f o r 3 9
parameters.
75
Drinking water 2010
SSE Water
Water suppl y arrangements
Comp an y a s set s
Num ber of tr e atm en t w or k s
0
Num ber of s er v ic e r es er vo ir s
0
Num ber of wat er s u p pl y zo n e s
6
Le n gt h of m ai ns p i pe ( k m )
9
W ate r s upp li ed
W ater s u pp l i e d
0. 2 6
( M l/ d a y)
P erc e n ta g e f rom
50
s urf ac e s ou rc es
P erc e n ta g e f rom
47
gro u n d s ourc es
P erc e n ta g e f rom
3
m ix ed s o urc es
Ar e a of supp l y
O ld S a rum , ne a r S al i sbu r y ;
Ha le Vi ll ag e, T otten h am ; G ra yl ingw e ll ,
Chi ch e ste r; B ro ml e y Com mon ,
Br oml e y; K enn et I sl a nd, R ea din g ; P a rk
Vi ew s, Ep som
Pop ul at i on s erv ed
P op u l at i on s u p p li e d
2, 0 00
Num ber of l oc a l au t ho r it i es
6
Drinking w ater qualit y summar y data
O v er al l dr in ki ng w at e r q ua lit y*
W ate r t re at m ent
Pr oc es s C o n tr o l I nd ex
Dis i nf ec ti o n In d ex
Di st rib ut io n s yst em s
Dis tr ib u t io n M a in t en a n c e In d ex
Res er v o ir In te gr i t y In d ex
Bui ldi ng w at e r s yst e ms
P aram et er s i nf l u enc e d b y d om es t i c
wa ter s ys t em s
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
10 0%
10 0%
10 0%
Indu st r y av e ra ge
20 1 0
99 . 96 %
N/ A
N/ A
N/ A
N/ A
N/ A
N/ A
99 . 99 %
99 . 97 %
10 0%
N/ A
10 0%
N/ A
10 0%
N/ A
99 . 86 %
99 . 96 %
10 0%
10 0%
10 0%
99 . 89 %
Consumer contacts
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
Info rm ing c on sum e rs
T ota l n um ber
0
1
1
Ra te per 1 , 00 0 p o pu l a ti o n
0
0. 7 4
0. 5
Ac c e pt abi lit y of w at e r t o
con su me r s
T ota l n u m ber
0
0
2
Ra te per 1 , 00 0 p o pu l a ti o n
0
0
0. 9 9
Comp l aint s t o t he D r i nki ng W at e r In spe cto ra te
No c o ns um er s of S S E W ater d ir ec t l y c o nt ac t ed DW I in 2 01 0 .
Indu st r y av e ra ge
20 1 0
N/ A
1. 2 6
N/ A
1. 9 8
Note: Summary results for each company of tests for individual parameters are supplied on
t h e DW I we b s i t e a t w w w . d w i . g o v . u k
* O v e r a l l d r i n k i n g wa t e r q u a l i t y a s r e p r e s e n t e d b y m e a n z o n a l c o m p l i a n c e f o r 3 9 p a r a m e t e r s .
76
Western region
South West Water Ltd
Water suppl y arrangements
Comp an y a s set s
Num ber of tr e at m en t w or k s
33
Num ber of s er v ic e r es er vo ir s
31 2
Num ber of wat er s u p pl y zo n e s
32
Le n gt h of m ai ns p i pe ( k m )
15 , 00 0
Pop ul at i on s erv ed
P op u l at i on s u p p li e d
1, 6 82 ,0 0 0
Num ber of l oc a l au t ho r it i es
13
W ate r s upp li ed
W ater s u pp l i e d
44 4
( M l/ d a y)
P erc e n ta g e f rom
84
s urf ac e s ou rc es
P erc e n ta g e f rom
6
gro u n d s ourc es
P erc e n ta g e f rom
10
m ix ed s o urc es
Ar e a of supp l y
Dev on , Co rnw al l, So me r set (p a rt),
Do rs et (pa rt)
Drinking w ater qualit y summar y data
O v er al l dr in ki ng w at e r q ua lit y*
W ate r t re at m ent
Pr oc es s C o ntr o l I nd ex
Dis i nf ec ti o n In d ex
Di st rib ut io n s yst em s
Dis tr ib u t io n M a in t en a n c e In d ex
Res er v o ir In te gr i t y I n d ex
Bui ldi ng w at e r s yst e ms
P aram et er s i nf l u enc e d b y d om es t ic
wa ter s ys t em s
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
99 . 98 %
99 . 98 %
99 . 97 %
Indu st r y av e ra ge
20 1 0
99 . 96 %
10 0%
99 . 94 %
10 0%
99 . 98 %
10 0%
99 . 97 %
99 . 99 %
99 . 97 %
99 . 89 %
99 . 93 %
99 . 91 %
99 . 93 %
99 . 89 %
99 . 93 %
99 . 86 %
99 . 96 %
99 . 95 %
99 . 97 %
99 . 91 %
99 . 89 %
Consumer contacts
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
Indu st r y av e ra ge
20 1 0
Info rm ing c on sum e rs
T ota l n um ber
2, 1 06
1, 9 51
1, 8 12
Ra te per 1 , 00 0 p o pu l a ti o n
1. 3 4
1. 1 6
1. 0 8
Ac c e pt abi lit y of w at e r t o
con su me r s
T ota l n um ber
19 , 22 3
14 , 67 5
11 , 08 5
Ra te per 1 , 00 0 p o pu l a ti o n
12 . 24
8. 7 2
6. 5 9
Comp l aint s t o t he D r i nki ng W at e r In spe cto ra te
A t ot a l of 4 c o ns um er s of S ou t h W es t W ater Lt d d ir ec t l y c o nt ac te d DW I in
N/ A
1. 2 6
N/ A
1. 9 8
2 0 10 .
Note: Summary results for each company of tests for individual parameters are supplied on
t h e DW I we b s i t e a t w w w . d w i . g o v . u k
* O v e r a l l d r i n k i n g wa t e r q u a l i t y a s r e p r e s e n t e d b y m e a n z o n a l c o m p l i a n c e f o r 3 9
parameters.
77
Drinking water 2010
Veolia Water Projects Ltd
Water suppl y arrangements
Comp an y a s set s
Num ber of tr e atm en t w or k s
2
Num ber of s er v ic e r es er vo ir s
6
Num ber of wat er s u p pl y zo n e s
1
Le n gt h of m ai ns p i pe ( k m )
98
W ate r s upp li ed
W ater s u pp l i e d
( M l/ d a y)
P erc e n ta g e f rom
s urf ac e s ou rc es
P erc e n ta g e f rom
gro u n d s ourc es
P erc e n ta g e f rom
m ix ed s o urc es
Ar e a of supp l y
T idw orth, W il tsh i re
Pop ul at i on s erv ed
P op u l at i on s u p p li e d
8, 0 00
Num ber of l oc a l au t ho r it i es
1
6
0
10 0
0
Drinking w ater qualit y summar y data
O v er al l dr in ki ng w at e r q ua lit y*
W ate r t re at m ent
Pr oc es s C o ntr o l I nd ex
Dis i nf ec ti o n In d ex
Di st rib ut io n s yst em s
Dis tr ib u t io n M a in t en a n c e In d ex
Res er v o ir In te gr i t y In d ex
Bui ldi ng w at e r s yst e ms
P aram et er s i nf l u enc e d b y d om es t ic
wa ter s ys t em s
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
N/ A
10 0%
10 0%
Indu st r y av e ra ge
20 1 0
99 . 96 %
N/ A
N/ A
10 0%
10 0%
10 0%
10 0%
99 . 99 %
99 . 97 %
N/ A
N/ A
10 0%
10 0%
10 0%
10 0%
99 . 86 %
99 . 96 %
N/ A
10 0%
10 0%
99 . 89 %
Consumer contacts
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
Indu st r y av e ra ge
20 1 0
Info rm ing c on sum e rs
T ota l n um ber
0
16
1
N/ A
Ra te per 1 , 00 0 p o pu l a ti o n
N/ A
1. 7 4
0. 1 2
1. 2 6
Ac c e pt abi lit y of w at e r t o
con su me r s
T ota l n um ber
0
3
6
N/ A
Ra te per 1 , 00 0 p o pu l a ti o n
N/ A
0. 3 3
0. 7 3
1. 9 8
Comp l aint s t o t he D r i nki ng W at e r In spe cto ra te
No c o ns um er s of V e o li a W ater Proj ec ts L t d d ir ec t l y c o nt ac t e d DW I i n 2 01 0.
Note: Summary results for each company of tests for individual parameters are supplied on
t h e DW I we b s i t e a t w w w . d w i . g o v . u k
* O v e r a l l d r i n k i n g wa t e r q u a l i t y a s r e p r e s e n t e d b y m e a n z o n a l c o m p l i a n c e f o r 3 9 p a r a m e t e r s .
78
Western region
Wessex Water Services Ltd
Water suppl y arrangements
Comp an y a s set s
Num ber of tr e atm en t w or k s
91
Num ber of s er v ic e r es er vo ir s
30 3
Num ber of wat er s u p pl y zo n e s
91
Le n gt h of m ai ns p i pe ( k m )
11 , 00 0
Pop ul ati on s erv ed
P op u l at i on s u p p li e d
1, 3 05 ,0 0 0
Num ber of l oc a l au t ho r it i es
15
W ate r s upp li ed
W ater s u pp l i e d
35 4
( M l/ d a y)
P erc e n ta g e f rom
27
s urf ac e s ou rc es
P erc e n ta g e f rom
71
gro u n d s ourc es
P erc e n ta g e f rom
2
m ix ed s o urc es
Ar e a of supp l y
La rg e p a rt s of S om e r set , Do r set and
W ilt shi r e, sm al l a re a s o f
G lou ce st e rs hi r e and Dev on
Drinking w ater qualit y summar y data
O v er al l dr in ki ng w at e r q ua lit y*
W ate r t re at m ent
Pr oc es s C o ntr o l I nd ex
Dis i nf ec ti o n In d ex
Di st rib ut io n s yst em s
Dis tr ib u t io n M a in t en a n c e In d ex
Res er v o ir In te gr i t y In d ex
Bui ldi ng w at e r s yst e ms
P aram et er s i nf l u enc e d b y
dom es t ic wat er s ys t em s
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
99 . 96 %
99 . 95 %
99 . 98 %
Indu st r y av e ra ge
20 1 0
99 . 96 %
10 0%
99 . 96 %
10 0%
99 . 90 %
> 99 . 99 %
99 . 95 %
99 . 99 %
99 . 97 %
99 . 97 %
99 . 95 %
99 . 97 %
99 . 97 %
99 . 97 %
99 . 98 %
99 . 86 %
99 . 96 %
99 . 81 %
99 . 80 %
99 . 94 %
99 . 89 %
Consumer contacts
Comp an y fig ur e
20 0 8
20 0 9
20 1 0
Indu st r y av e ra ge
20 1 0
Info rm ing c on sum e rs
T ota l n um be r
2, 8 59
1, 1 57
1, 0 51
N/ A
Ra te per 1 , 00 0 p o pu l a ti o n
2. 4 2
0. 9 8
0. 8 1
1. 2 6
Ac c e pt abi lit y of w at e r t o
con su me r s
T ota l n um ber
3, 6 39
3, 8 45
3, 2 24
N/ A
Ra te per 1 , 00 0 p o pu l a ti o n
3. 0 8
3. 2 6
2. 4 7
1. 9 8
Comp l aint s t o t he D r i nki ng W at e r In spe cto ra te
No c o ns um er s of W ess ex W ater Ser v ic es L t d d irec t l y c o nt ac t e d D W I in 20 1 0.
Note: Summary results for each company of tests for individual parameters are supplied on the
DW I we b s i t e a t w w w . d wi . g o v . u k
* O v e r a l l d r i n k i n g wa t e r q u a l i t y a s r e p r e s e n t e d b y m e a n z o n a l c o m p l i a n c e f o r 3 9 p a r a m e t e r s .
79
Drinking water 2010
Drinking water
2010
Public water supplies in the
Western region of England
July 2011
A report by the Chief Inspector of Drinking Water
Public water supplies in the Western region of England
Drinking
Water Inspectorate
| Ergon House,
Horseferry
Road | |London
| SW1P
2AL
| Tel:
030
0068 6400
Drinking
Water Inspectorate
| 55, Whitehall
| London
SW1A 2EY
| Tel:
020
7270
3370
www.dwi.gov.uk
http://www.dwi.gov.uk
PB13481