Alternative Water Systems Information Leaflet and

Alternative
Water Systems
Information Leaflet
and Guide
Contents
3Introduction
3 What do we mean by alternative water?
3 Rainwater harvesting – what is it?
3 Greywater – how is it different?
3 What other sources can be used?
4 Standards and regulation
4 Are there any standards?
4 What regulations apply?
4 Notification to Water Companies
4 Do I need to tell the local Water Company about my installation?
5 System designs
5 Direct systems
5 Indirect systems
6 Back-up water supply
6 What happens when there is no rain?
6 What would happen if there was no mains water back-up supply?
7 Backflow protection
7 What sort of risk are alternative waters?
7 What backflow protection is required for the mains water back-up supply?
7 Clothes washing machines
7 Examples of backflow protection
8 Dead legs
8 Additional protection
9Pipework
9 Do I need special pipework?
9 Below ground pipework. What should I use?
9 What about contaminated land?
9 Above ground pipework. What should I use?
10 Labelling and marking
10 Why do I need labels?
10 Colour coding pipework
10 Why must you colour code all water alternative pipework?
10 The following methods are recommended:
10 Commercial/Industrial pipes
10 Domestic pipes
11Labelling
12Maintenance
12 Do these systems need maintenance?
12Summary
12 Other references
12Acknowledgements
2
Introduction
A
lternative water sources are more commonly being considered for use in homes and
business premises as customers become more Waterwise. In recent years the Water
Industry has become aware of an increasing level of alternative systems, particularly
borehole supplies and rainwater harvesting units, that have been installed incorrectly
or have not been adequately maintained, leading to serious public health risks at the
properties involved, and potential wider risk to public water supplies.
The following guidance covers the key areas which must be adhered to and areas that need
careful consideration for anyone designing installing and using these systems.
What do we mean by alternative water?
Alternative water covers a wide variety of sources from bore holes, river water, industrial process
water, as well as Water Reuse systems.
Water Reuse is the new term for what we used to know as water recycling or reclaimed water,
and covers rainwater harvesting as well as greywater treatment.
The purpose of these systems is to provide an alternative to mains drinking water that can be
used for processes, or appliances that do not need such high quality water, as promoted in the
2010 revision of Part G of the Building Regulations. This allows for non-wholesome water to
be used for the first time, thereby trying to help reduce the reliance on public mains water.
The most common systems used in the UK are rainwater harvesting, greywater treatment,
and bore holes.
Rainwater harvesting – what is it?
In simple terms it is a means for diverting rainwater that falls on roofs, or other collection
surfaces of a property, and storing it, usually in an underground tank, for later reuse.
Collected rainwater will contain traces of atmospheric and environmental pollutants, and is
likely to contain some animal and bird faecal matter. The extent of such contamination will vary
from site to site but some degree of contamination must always be assumed.
Greywater – how is it different?
Greywater is the wastewater from domestic pipes and fittings in our homes and businesses,
but excludes the wastewater from toilets and urinals, which is known as blackwater because
it is likely to contain faecal matter, and bodily wastes.
Greywater can be sub-divided by the source, kitchen greywater is likely to contain high levels
of fats, greases and organic matter, whereas bathroom greywater is the less polluted greywater
from baths, showers and wash hand basins and it is this bathroom greywater which is
normally collected for treatment and reuse.
What other sources can be used?
There are a great many sources of water that can be used, but it is often the amount of
treatment needed to bring it up to a suitable safe level that limits its use.
Whilst in most cases groundwater sources are relatively clean and can be used without
treatment for irrigating crops and for animal drinking water, they are not sealed systems and
so it cannot be assumed that they will be contamination free.
3
Standards and Regulation
Notification to Water Companies
Are there any standards?
Do I need to tell the local Water Company
about my installation?
Yes, British Standards have published two documents,
BS8515:2009 for rainwater harvesting systems and
BS8525-1:2010 for greywater systems. These recently
published standards cover the design, installation and
maintenance requirements for these water alternative
systems and include water quality requirements for the
end uses, and are some of the first in Europe.
For other sources there are currently no set standards,
however the Private Water Supply Regulations cover
the use of abstracted water intended for human
consumption and food production. They cover
water quality requirements and in essence mirror the
requirements set out for public drinking water standards.
What regulations apply?
In addition to the British Standards the requirements of
the Water Supply (Water Fittings) Regulations 1999 do
apply to properties that have alternative water supplies,
(whilst these Regulations apply in England and Wales
similar requirements apply in Scotland and Northern
Ireland under their own Byelaws and Regulations), and
are intended to protect public health and to make
sure there is no waste, misuse, undue consumption,
contamination or erroneous measurement of public
mains water.
4
Normally Approved Plumbers would not have to notify
such installations, however some water companies are
maintaining records of such systems because of recent
problems, so it is worth contacting them to make sure
you understand what the local requirements are prior to
the installation.
System Designs
This guide covers some of these requirements and gives
examples of good practice.
an easily accessible manual by-pass valve is
installed so it can turn the ball valve on.
In general there are two basic design types for
alternative water systems that are commonly used to
distribute water to the end use appliances, direct and
indirect, and they both have their merits and drawbacks.
Whilst this type of system can easily cope
with a failure be it electrical or a system
fault, it does require some space to locate
the high level storage cistern and additional
plumbing.
Direct systems
This is where water is pumped directly from a borehole
or storage such as the underground tank, direct to the
points of use, for example toilets and outside taps.
This system typically provides low pressure
water to the appliances and potentially low
flow rates which can be overcome by good
design and tap selection etc.
In the event of a failure in any of the sensors, pumps,
controls or a power cut there will be no water for the
appliances supplied, for example, toilets, outside taps
etc. Even the mains water back-up would be of no help,
as this normally fills into the low level storage tank or
treatment system and needs further pumping. This is
the direct system’s Achilles heel, however on the positive
side it can be easier to install and take up less space as
there is no need for any extra plumbing such as high
level cisterns etc.
It is necessary that whatever alternative
source of water has been selected the
treatment system used must be able
to deliver an appropriate level of water
quality for the end use to ensure the users
are not exposed to undue risks. British
Standards have set health based water
quality requirements for the supply of both
rainwater and greywater.
Indirect systems
This is where the alternative water is pumped from the
borehole or storage tank up to an intermediate cistern at
high level, for example in the roof space, from where it
can then feed by gravity to the points of use.
By having the mains water backup connected into this
cistern it can be made to change over seamlessly in the
event of a problem with the system or a power failure.
To make sure this will work it is essential to ensure the
solenoid valve on the back-up supply is of a type that
will open when there is no electrical power to it or, that
Typical systems with automatic back-up and manual override.
5
Back-Up Water Supply
What happens when there is no rain?
All rainwater harvesting is reliant on frequent rainfall,
and this will vary across the country. Even the areas of
the country with the highest rainfall will experience
dry periods. So when this happens it is essential to
have a mains water back-up supply to keep
appliances operating.
Greywater systems are reliant on occupiers using baths,
showers etc to provide it with the untreated greywater,
so this should not be a problem. However should there
not be enough untreated greywater to process, or the
treatment system fails for some reason, it should be
designed so that it is able to continue to operate by
providing an alternative supply. Again it will be
essential for this to be provided for by a mains water
back-up supply.
What would happen if there was no mains water
back-up supply?
If an alternative water system failed or there was no
alternative water to supply it, the system would stop
working. Users would not be able to flush their toilets
or use other appliances, which could potentially lead
to public health issues. So it is important that whatever
design is chosen at least one toilet must be able to
operate normally. It is recommended in larger premises
that this is supplied direct from the mains water supply if
the design does not incorporate a reliable alternative.
An example of a mains back-up supply unit.
Where a back-up water supply is used it should be
controlled so that only the minimum amount of water is
supplied to the system, particularly if it is being put into a
rainwater tank. This will ensure that when it next rains the
maximum amount can be captured.
Where the back-up water is delivered to below ground
storage, consideration should be given to the potential
for smells to vent back in to the property. A mechanical
waterless trap may be used to prevent this occurring.
6
An example of poor installation, with no marking to clearly identify
rainwater from mains water.
Backflow Prevention
What sort of risk are alternative waters?
Essentially all alternative water supplies must be
considered a fluid category 5 risk, that is to say it poses
a serious health hazard.
Rainwater will contain atmospheric pollution and due to
the nature of the surfaces from which rain is collected,
means it is also likely to contain faecal, biological or
pathogenic contaminants. Similarly greywater and
collected wastewater from washing etc., is also likely to
contain faecal and pathogenic organisms.
Other alternative water supplies from bore holes and
rivers are likely to have a wider range of pathogenic
organisms and possibly faecal matter and are therefore
placed in the same category.
A cross-connected borehole supply pumped
unwholesome water into the public mains
supply (now disconnected) because of the
difference in supply pressures.
To make sure users are always fully protected
a permanent protection arrangement or
device needs to be used. Reputable system
manufacturers provide Category 5 backflow
protection in their back-up water system.
Clothes washing machines
What backflow protection is required for the mains
water back-up supply?
However there is one area where caution is
needed, clothes washing machines; these can
be supplied from alternative water systems
provided they can produce the high quality
of treated water needed, and this is becoming
more common.
Fluid category 5 protection is required and can only be
achieved through the installation of either a Type AA,
AB or AD air gap, or through the use of a Type DC pipe
interrupter (a device which incorporates an air gap), to
separate the mains water supply and the alternative water
system. The most common methods are through a
Type AA or AB air gap.
Whilst new washing machines typically
only come with a cold fill connection, older
machines have two feeds. Standard domestic
machines do not have the fluid category 5
protection capability that is needed; therefore
these must not be connected to both domestic
hot/cold water and the alternative water.
It must be noted that no mechanical devices are capable
of protecting against this level of risk. Therefore no direct
or removable cross-connections are allowed.
You can only connect to a washing machine
that has suitable backflow protection for fluid
category 5 and these are not readily available
in the UK.
Example of how not to connect water from a bore hole to a
mains backup (now disconnected).
Examples of type AB air gaps.
Water supplied by
Water Suppliers
Type AA, AB or AD air
gap to be provided
SgV
Bore hole supply
Spillover level
Warning pipe
Supply
to farm
Supply to barn
Water not supplied by
Water Suppliers or
non-potable water
CV
6/R15.30b
24.11.99 okay
Pipe
interrupter
Not less than
300mm min.
Mains water supply
(now disconnected)
7
6/G15.31.12
10.11.99 & okay
SL
Outlet
Backflow Prevention
Whole site protection by double check valve.
Dead legs
In normal operation the back-up supply should not be
needed on a regular basis, and so this low frequency
use will offer the opportunity for water to stagnate and
should be avoided. Where this is not avoidable, additional
backflow protection, such as a single check valve, must
be installed at the branch supplying the back-up supply
system to protect the drinking water supply.
Additional Protection
Some Water Undertakers may require additional backflow
protection to ensure cross contamination between
premises is adequately prevented.
It is therefore essential that the local Water Undertaker is
consulted as to their requirements prior to installation.
Additional protection on the incoming mains supply.
Direct system mains water back-up supply
Type AA air gap
Tundish
Water from re-use
system to appliances
Supply to water
re-use system
Indirect system mains water back-up supply
Type AB air gap
weir overflow
Fluid Category 5
(Rainwater/greywater)
Water from re-use
system to appliances
8
Supply from
water re-use
system
Pipework
Do I need special pipework?
Pipes must be made from materials that are suitable for
location, temperature range, and the type and quality of
the alternative water to be used. This will ensure there are
no adverse effects, for example corroding pipework, due
to factors such as low pH or other chemical effects. British
Standard recommend that a contrasting type or colour of
pipework is used to make it easy to identify.
Example of below ground pipe
Below ground pipework. What should I use?
For pipework below ground a contrasting colour for
alternative systems must be used.
The Water Regulations Advisory Scheme (WRAS) and
National Joint Utilities Group (NJUG) recommend that
black pipe with green stripes is used, this is detailed in the
recently revised WRAS Information and Guidance Note
No 9-02-05 and meets these requirements.
Following these recommendations will ensure that buried
pipes can be easily identified during any subsequent
excavations.
This pipe has recently been introduced into the UK by
member companies of the UK Rainwater Harvesting
Association (UKRHA) and specialist suppliers, more
recently it is appearing in major building merchants
as well.
What about contaminated land?
Where pipework is laid in contaminated ground the pipe
must also be of a type that is resilient to any potential
contamination that would have a detrimental effect
on either the pipe, any fittings to be supplied, or if it
permeated into the alternative water supply would make
it unsuitable for the intended uses.
Above ground pipework. What should I use?
Current standards do recognise that normal plumbing
pipework will be used for alternative water systems,
however they do recommend that a contrasting type
or colour is used to prevent confusion with the normal
plumbing system.
Some manufacturers are currently considering the
feasibility in making pre-marked pipework for internal use.
9
April 2011
No 9-02-05
INFORMATIO
N&
GUIDANCE
NOTE
1. Introduction
ISSUE 2
Marking & Ide
ntification of
Pipework for
Water
Reuse Syste
ms
Water reuse
is
reducing wate an accepted method
world
r
which is treate demand. Rainwater and wide for
Code of pract
d wastewater
greywater
ice' have been
and sinks,
ensure comp
developed
are increasing from showers, baths
liance with
reused for
ly being collec
the requireme to both
Regulations
applications
ted and
and the adop
nts of the
wholesome
which do
tion of best pract
water, such
not require
ice.
as laundry,
and garden
This inform
WC flushing
watering. In
ation guida
sources of
addition to
nce note (IGN)
colour codin
water such
these, other
g
and marking
details the
as blackwate
sewage efflue
ensure that
identification
r (recycled
nt) and indus
requi
intern
red to
considered
al
trial water
pipework
distribution netwo
for reuse.
are being
and external
the requireme rks conveying reused
water satisfy
nts
The purpose
with the appro of the Regulations
of the Wate
and comply
r
Regulations
provides inform priate British Stand
and Scottish Supply (Water Fittings)
ard. It also
ation regarding
Water Byela
referred to as
cister
signa
ns
ws (hereafter
and appliances.
the Regulation
ge for stora
misuse,
ge
s) is to preve
undue
nt waste,
consumption,
measurement
In exceptiona
and most impo
erroneous
l circumstanc
of drinking
rtantly conta
may be willing
es local water
water
mination
suppliers
to accept
result of backp . Contamination can
recommend
alternatives
occur as a
ation made
to the
which can causeressure or backsiphon
in this guida
any deviation
age, both of
nce; however
contaminants
must
pipework into
be
discu
to be draw
advance.
ssed and agree
d in
including that the water supply. Reus n back up
which has been
ed
to be fluid
treated, is consiwater,
categ
dered
pollutants posin ory 5 (the most dang
erous of
2. Reused wate
not under any g a serious health haza
r systems
rd) and must
circumstanc
into contact
es be allow
with the whole
ed to come
water supplies.
some dome
Because reuse
stic drinking
d water syste
the UK it is
important that ms are relatively new to
To reduce
ensure that
every effort
all pipework
the risk of
conveying reuseis made to
contamination
immediately
cross-connection
and easily
d water is
and
essential that of the wholesome water
identifiable
come acros
to those who
s it.
supply it is
It is there
readily distin all reused water pipew
wherever it
guishable from
ork is both
is located, pipew fore essential that,
instantly recog
water is both
other pipew
recognisable ork distributing reused
ork and
example inside nisable wherever it is
that supplying
and
distinguishable
located, for
wholesome
from
private land. a property, beneath the
contrasting
mains water
or
stree
.
The use of
different pipe
t, or on
operation, that So that accidental or
easier but
materials will
it will not
deliberate
could put the
make this
identify
risk, can be
contents, and
wholesome
avoided all
so irrespective the nature of the
apparatus such supply at
and washouts
used pipes
of the pipe
must be mark
on
as valves
material
should be suitab systems distributing
ed and labell
that all pipew
reused water
ed
ork
ly
to
mark
ensu
conve
ed and signif
re
ying
from those
water is distin
icantl
norm
guishable from unwholesome reused
distribution netwo ally used on whole y different
other pipework.
some water
rks.
New British
standards, BS
systems –
8525-1:2010
Part
‘Greywater
8515:2009 ‘Rain 1: Code of pract
ice’
water harve
sting systems and BS
–
3. Notification
Water supp
liers must be
grant conse
notified in adva
nt for the instal
nce and
lation of reuse
d water
Labelling & Marking
Why do I need labels?
Domestic pipes
Fitting labels and marking pipes will ensure users are
fully aware of what quality of water is being supplied to
their appliances. This will help users take the appropriate
precautions to ensure their family do not drink from taps
supplied with rainwater/greywater. This contributes to
the health and wellbeing not only for current users but for
future occupiers, by raising awareness that an alternative
water system has been installed.
Premises that only have smaller pipes, as
in most houses, should use these same
principles, but it is acceptable for it to be
scaled down to 150mm long. This will ensure
a common recognisable marking is used
across all properties and pipes can be readily
identified.
Colour coding pipework
Why must you colour code all water alternative pipework?
Colour coding of pipework is essential to help prevent
any possibility of misconnecting to an alternative water
system when carrying out work on the plumbing system.
It will also help prevent cross-connections that could lead
to contamination of the drinking water supply.
The following methods are recommended:
Insulated pipes should be labelled on the outer surface
of the insulation, regardless of whether the pipe has been
identified prior to insulation, and marking should be
designed for the life of the system. Marking can be made
at the time of manufacture or labelling attached during
installation.
Marking should be located along the length of the pipe at
not greater than 0.5 metre intervals and at key connection
points, but consideration should be given to pipes
running through joists or other enclosed areas to ensure
they can be readily identified.
Commercial/Industrial pipes
Large scale water pipelines, e.g. in commercial premises,
should be marked using the accepted principles set out
in BS1710, Identification of pipelines. The identification
colour should be green and black as shown below,
identifying it as carrying non-wholesome water from an
alternative water system.
10
Colours to BS 4800:1989;
Green - 12 D 45; Black - 00 E 53
Labelling and Marking
Labelling
Labelling with tags all taps and valves that supply
rainwater or greywater, ensures the users are made
aware an alternative water system is present. Point of
use appliances such as toilet cisterns, outside taps, and
washing machine connections should have point of
use labels indicating ‘Not drinking water’ . Also storage
cisterns should be labelled as containing alternative water
to make sure there is no confusion as to what is stored.
The minimum recommended sizing for outside or hose
union taps is 80mm high and for internal use 40mm.
Labels should be fitted to isolation valves and key points
that indicate supplies of different pressures, qualities, and
designated uses. The lettering on these labels should be
black on green as above and not less than 5mm in height.
11
Maintenance
Do these systems need maintenance?
Maintenance is vital to make sure maximum benefit can
be gained by users, and it is no less true for an alternative
water system. A few simple frequent checks may be
all that is needed to ensure a system functions at its
optimum, as the manufacturer intended.
It is critical that users are made aware of this and that it is
in their interests to follow the maintenance requirements
as specified by the manufacturer. If they fail to do this,
it could lead to either system failure or expose them to
increased levels of contamination in the water they
hope to reuse.
To ignore this can be critical. If a customer decides to
ignore this or even worse cross-connects to their mains
water supply, it can have severe consequences. It is
therefore critical these factors are considered during the
design stage when selecting the most suitable
alternative water system.
Summary
These alternative water supply systems can offer a way to
help save on mains water use, providing they are installed
correctly. More and more developers and builders are
seeking to install these types of systems in the latest
style eco-housing. To ensure that we all can exercise our
duties of care, please make sure you follow a few simple
checks to guarantee systems are installed properly by:
l Notifying water suppliers, where needed, in plenty
of time to prevent delays.
l Selecting a design that can ensure a constant
supply of water is available for critical appliances
such as toilets.
Other references
Copies of this guide can be downloaded free
from www.wras.co.uk
Water Regulations Advisory Scheme:
www.wras.co.uk
Water Supply (Water Fittings) Regulations
http://www.defra.gov.uk/environment/
quality/water/industry/wsregs99/index.htm
BS8515:2009
Rainwater Harvesting Systems Code of
Practice.
BS8525-1:2010
Greywater Systems Code of Practice.
l Use the correct pipe below ground.
BS1710:1984
Identification of Pipelines and Services.
l Make sure there are no cross-connections.
l Ensuring the backflow protection is of the
correct type.
BS4800:1989 Colours for Buildings
l Follow proper labelling and marking requirements.
National Joint Utilities Group www.njug.co.uk
l Follow the British Standard Codes of Practice.
Acknowledgements
l Make sure users are fully conversant with the systems,
particularly operation and maintenance requirements.
Regulation compliance images reproduced
by kind permission of Water Regulations
Advisory Scheme (WRAS).
l Water suppliers want to make sure that their
customers have a good healthy wholesome drinking
water supply, so having a well designed system
installed that meets the regulatory requirements
helps to serve this purpose.
12
Cover image courtesy of
RainWaterHarvesting.co.uk.