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Author’s full name :
INAWATI BINTI OTHMAN
Date of birth
:
1ST OCTOBER 1987
Title
:
DETERMINATION OF NON-REVENUE WATER THROUGH DISTRICT METER AREA
Academic Session :
2009/2010
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Date : 19TH APRIL 2010
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ASSOC. PROF.IR.HJH FATIMAH MOHD NOOR
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Date :19TH APRIL 2010
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Date
:
19 April 2010
i
DETERMINATION OF NON-REVENUE WATER THROUGH
DISTRICT METER AREA
INAWATI BINTI OTHMAN
A report is submitted in partial fulfillment of the requirements for the award of the degree of
Bachelor of Civil Engineering
Faculty of Civil Engineering
Universiti Teknologi Malaysia
APRIL 2010
ii
I declare that this thesis entitled “Determination of Non-Revenue Water Through District
Meter Area” is the result of my own research except as cited in the references. The thesis
has not been accepted for any degree and is not concurrently submitted in candidature of
any other degree.
Signature
:
.....................................
Name
:
Inawati Binti Othman
Date
:
19 April 2010
iii
Especially dedicated to:
My beloved dad and mom, Othman Tang@ Othman Bin Jafar Sider and Raniah Bt At,
My siblings, My Best friend forever and My beloved one ,
Thanks for supporting, understanding and concern…
I love you…
Supervisor, Assoc. Prof. Ir. Hjh. Fatimah Mohd Noor and Puan Azmahani Bt Abd. Aziz,
thanks for giving me the opportunity, priceless knowledge and advices to do research on
your guidance…
Last but not least, deepest appreciation to
Syarikat Air Johor and Ranhill Water Services utilities
in helping me collecting data.
iv
ACKNOWLEDGEMENT
Bismillahirrahmanirrahim, Alhamdulillah, Thanks to Allah S.W.T whom with His
willing giving me the strength to complete the thesis. I am heartily thankful to my
supervisor, Assoc. Prof. Ir. Hjh. Fatimah Mohd Noor and Puan Azmahani Bt Abdul Aziz,
whose encouragement, guidance and support from the initial to the final level enabled me
to develop an understanding of the research.
I would like to express my sincere gratitude to thank to Syarikat Air Johor, Puan
Noor Haffizah Binti Mohd Shah and Ranhill Water Services manager as my advisor for
the project. Without guide, critic and helping from them, this assessment may not
complete and fulfill the objective of study. I would like to show my gratitude to all of the
water uitilities at Johor Bahru and Batu Pahat.
Thanks to all my friends especially to my project team Azwan Bin Mustapha for
your best compliment and stick together to work as a group and help for the whole time
of the project.
Lastly, I offer my regards and blessings to my family members especially, my
mom and dad as well as my siblings and also my beloved one for their continuous
support and concern at anytime, anywhere and everything I need during the completion
of the thesis. Thank you very much to all of you. It is a pleasure to thank those who made
this research successfully done.
v
ABSTRACT
The world‟s population exploded during the twentieth century and was estimated
approximately 6.6 billion in February 2008.This situation has created mounting pressure
on water demand. Over the past few centuries, Malaysia does not face problem in scarcity
of water supply due to excessive annual rainfall. The abundant sources of water supplies
are decreased due to increasing of population and impressive economic growth. Currently
in Johor state, there is 32.46 % non-revenue water (NRW). Water pipeline leakages are
the main contributor in NRW percentage with almost 75-80% .This current paper focuses
on the assessment of NRW components in a District Metering Area (DMA) based on
collected data from Syarikat Air Johor utility. Water losses have been assessed by
calculation based on the analysis of Minimum Night Flows in Step Test and using Water
Audit in DMA which covers predominantly two adjacent residential areas in Batu Pahat.
The paper moots the factors which influence NRW components and strategies can be
developed for curtailing the NRW. Results have shown that both methods have their own
advantages and disadvantages in order to eradicate high level of NRW and both areas
studied had been reduce in NRW after implementing DMA methods. However from this
assessment, the Water Audit method is recommended.
vi
ABSTRAK
Populasi dunia meledak naik pada abad dua puluhan dan dijangka sebanyak 6.6
bilion pada Februari 2008. Situasi ini telah meningkatkan kadar permintaan air. Beberapa
abad lalu,
Malaysia tidak berhadapan dengan masalah kekurangan permintaan air
disebabkan oleh kadar hujan tahunan yang tinggi. Punca bekalan air yang dahulunya
banyak semakin berkurangan disebabkan oleh peningkatan jumlah penduduk dan
pertumbuhan ekonomi yang menggalakkan. Kini, sebanyak 32.46 % kehilangan air tanpa
hasil berlaku di negeri Johor. Punca utama yang menyumbangkan kadar kehilangan air
tanpa hasil ini adalah paip bocor sebanyak 75-80 peratus. Kajian ini membincangkan
komponen kehilangan air tanpa hasil dengan menggunakan kaedah „District Meter
Area‟(DMA) berdasarkan kepada dapatan data dari Syarikat Air Johor. Kajian berikutan
kehilangan air berdasarkan kepada analisis „Minimum Night Flow‟(MNF) dan juga
keseimbangan air dalam DMA yang meliputi dua kawasan perumahan yang berdekatan di
Batu Pahat. Perbincangan kajian ini merangkumi faktor-faktor dan strategi untuk
merendahkan aras kehilangan air tanpa hasil. Keputusan menunjukkan kedua-dua kaedah
mempunyai kelebihan dan kekurangan masing-masing dalam usaha menurunkan aras
kehilangan air tanpa hasil untuk kedua-dua kawasan. Kedua-dua kawasan kajian
mengaplikasikan
kaedah
DMA
dan
penurunan
kehilangan
air
tanpa
dibuktikan.Walaubagaimanapun,kaedah Audit Air dicadangkan untuk kajian ini.
hasil
vii
TABLE OF CONTENTS
CHAPTER
1
2
TITLE
PAGE
TITLE PAGE
i
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENTS
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
x
LIST OF FIGURES
xi
LIST OF APPENDICES
xii
INTRODUCTION
1
1.1
Introduction
1
1.2
Problem Statement
3
1.3
Objectives of Research
3
1.4
Scope of Study
4
LITERATURE REVIEW
8
viii
2.1
Introduction
8
2.2
Definition of Non-Revenue Water
9
2.3
Definition of Apparent Losses
10
2.3.1 Elements of Apparent Losses
10
2.3.2 Inefficiency in Customer Meter
12
2.3.3
Unauthorized Consumption
12
2.3.4
Customer Meter Inaccuracy
13
2.4
Definition of Real Losses
14
2.4.1
14
Elements of Apparent Losses
2.4.1.1Leakage
from
transmission
and
distribution
15
2.4.1.2 Leakage and overflow from
utility‟s reservoirs and storage tanks
16
2.4.1.3 Leakage on service connections
up to the customer‟s meter
17
2.4.2
Characteristics of Leakages
17
2.4.3
Types of Leakage
19
2.4.3.1 Crack
19
2.4.3.2 Pinhole
20
2.4.3.3 Seepage
20
2.4.3.4 Pipe Joint Leaks
20
2.4.4
Management Tools for Real Losses
Reduction
21
2.4.4.1 Unavoidable Annual Real Losses
(UARL)
2.4.5
Active leakage control (ALC)
21
23
ix
2.5
Introduction to District Meter Area (DMA)
24
2.5.1 Criteria and process of DMA
establishment
25
2.5.2 Initial DMA installation and testing
26
2.5.3
26
DMA meter selection
2.5.4 District Meter Area installation
3
4
procedure
27
2.5.5
DMA data monitoring
28
2.5.6
DMA Data Analysis
29
2.6
Step Test Method
30
2.7
The 2008 Annual Water Balance for Johor
32
2.8
Percentage of Non Revenue Water (%)
33
RESEARCH METHODOLOGY
35
3.1
Introduction
35
3.2
Study Flow Process
35
3.3
Case Study
38
3.4
Data Acquisition and calculation
39
RESULTS AND DISCUSSIONS
41
4.1
Results of NRW
41
4.2
„T‟ factor for Taman Batu Pahat Area BP39
42
4.3
Leakage Percentage using Step Test Method
46
4.4
Non Revenue Water percentage using Water
4.5
Audit Method
49
Discussions
53
x
5
CONCLUSIONS AND RECOMMENDATIONS
5.1
5.2
REFERENCES
Appendices A and B
Conclusions
57
5.1.1
NRW components are identified
58
5.1.2
Implementing
District
Meter
Area
method in determination of NRW
58
Recommendations
59
61
62-64
xi
LIST OF TABLES
NO.
TITLE
PAGE
2.1
Flow rates for reported and unreported bursts
15
2.2
Calculating background losses
16
2.3
The 2008 Annual Water Balance for Johor
33
2.4
Percentage of Non Revenue Water (%)
34
4.1
Network properties for each zone
42
4.2
Average pressure and leakage index for area BP39
43
4.3
Relationship between leakage (net night flow) and pressure
44
4.4
Average pressure and leakage index for Taman Makmur BP40
45
4.5
Leakage percentage of BP39 and BP40 for 2009
46
4.6
4.7
Sample Computation of Leakage Percentage on January on
Taman Batu Pahat, BP39
Non Revenue Water using Water Audit Method
47
49
xii
LIST OF FIGURES
NO.
TITLE
PAGE
1.1
The Location of Study Area
5
1.2
Schematic Drawing for Taman Batu Pahat, BP39
6
1.3
Schematic Drawing for Taman Makmur, BP40
7
2.1
“IWA Best Practice” Water Balance and Terminology
9
2.2
10
2.3
Four Pillars of apparent losses
Leak duration and flow of water loss
2.4
Leak run time and volume of water loss
18
2.5
The Four Basics Methods of Managing Real Losses
21
2.6
Typical losses from a water supply system
22
2.7
A typical distribution network
23
2.8
A typical DMA design
24
3.1
Procedure Flow
37
3.2
Water utility manually read customer meter
40
4.1
Minimum Night Flow for BP39 and BP40
48
4.2
Water production of Taman Batu Pahat, Bp39 and Taman
18
Makmur, BP40
51
4.3
Leakage and NRW percentages for Taman Batu Pahat, BP39
52
4.4
Leakage and NRW percentages for Taman Makmur, BP40
53
4.5
NRW for BP39 and BP40 by Water Audit Method
55
xiii
APPENDICES
APPENDIX
TITLE
PAGE
A
Water Supply System Drawing
62
B
Site Visit Photos
63
CHAPTER 1
INTRODUCTION
1.1
Introduction
The world‟s population exploded during the twentieth century and was estimated
approximately 6.6 billion in February 2008. [1] This situation has created mounting
pressure on water demand. Over the past few centuries, Malaysia does not face problem
in scarcity of water supply due to excessive annual rainfall. The abundant sources of
water supplies are decreased due to increasing population and impressive economic
growth. Water losses are allowed to be largely overlooked because its abundance. With
water readily available and relatively inexpensive, losses have been ignored by water
utilities or assumed to be naturally inherent in operating a water supply system. However,
the availability of water could not continue to sustain this rate of growth indefinitely.
The urban population of the country is expected to increase rapidly because of the
growing migration from the rural area. In rural areas water is used for such activities like
agricultural, livestock, small industrial activities, domestics and outdoors. Water is
supplied from hydraulic structures such as dams, reservoirs, and tanks to serve this
2
purpose. Water supply flows via the underground pipelines along the roads and
highways. The water distribution system is organized in a network of pipes made of
Asbestos Cement (AC), Polyvinyl Chloride (PVC), High Density Polyethylene (HDPE),
Ductile Iron (DI) and mild steel in many countries. [1]
Any disturbance that occurs in the water distribution system lead to the crucial
problem that might affect the users. These pipelines are exposed to nature activities and
will deteriorate. Deterioration and damaged are caused by soil movement, corrosive
environments, fluctuation of water pressure, construction not complying with the
standards and excessive in traffic loading. Due to these factors, pipelines are exposed to
the ground, cracks, leaks and burst. These situations are contributing to the water losses
in pipelines.
Water loss is defined as losing some amount of water in pipeline distribution
system. Water loss is a universal problem and occur in both developed and developing
countries. Loss in water distribution system is referred to unaccounted for water (UFW)
and now known as non-revenue water (NRW). NRW is basically defined as losing some
amount of water in pipeline distribution networks. NRW technically defined as the
difference between water delivered to the distribution system and water being sold by the
utility based on meter consumption. According to the standard International Water
Association (IWA), NRW is the sum of real and apparent losses plus unbilled authorized
consumption.
One of the major challenges facing water utilities in the developing world is the
high level of water loss due to pipe bursts and leakages, theft of water from the system, or
water users not billed properly. The major contributor to non-revenue water in Malaysia
is pipeline leakage. Pipe leakage categorized by real losses. How much water is being lost
from water network and where the losses are occurring is crucial to water utilities. Water
3
loss could occur in different part of the components such as distribution pipes,
transmission pipes, service connection pipes, joints, valves, fire hydrants and storage
tanks and reservoirs.
Malaysia Water Industry Guide (2007), under the 9 th Malaysia Plan (9MP), the
government promises sufficient water supply to the rural areas. Moreover, under 9MP,
water supply projects are to be allocated RM8.2 billion increase from the RM3.88 billion
allocated under 8MP. The government of Malaysia has implemented strategy to
rehabilitate the distribution network to bring down the level of NRW from 38% in 2005
to 30% by 2010. Other than that, the government plan to replace about 12 000 km of
existing aged Asbestos Cement Pipes and old cast iron pipes with Unplasticized
Polyvinyl Chloride (uPVC).[2]
1.2
Problem Statement
Rapid urbanization and increasing number of population will lead to higher
demand of water and thus leads to the problem of water losses. The amount of water
losses cannot be completely avoided. However they can be managed to remain in
economic limits. Improvement in a performance of managing water losses can be
achieved through replacing aging infrastructure and establishing District Meter Areas or
District Meter Zones (DMA/DMZ) and using them to manage NRW. Therefore, the
reduction and control of water losses is vital to minimize NRW levels that threaten the
long term sustainability of water resources for the future.
4
1.3
Objectives of Research
The main objective of this study is to analyze the existing problem of non-revenue
water (NRW) in distribution system and identify the real losses components and apparent
losses components in these areas. Next is to propose District Meter Area (DMA) methods
in reduction of NRW such as Step test and Water audit methods and also make
comparisons between two adjacent residential areas with two different methods.
1.4
Scope of Study
Figure 1.1 shows the location of study area.The study areas selected are at Taman
Batu Pahat and Taman Makmur at Batu Pahat, Johor. Figure 1.2 shows schematic
drawing for Taman Batu Pahat, BP39 while Figure 1,3 shows schematic drawing for
Taman Makmur, BP40. The scopes for this study include review the existing data and
information for these study areas. Data using for this study is one year data from January
to December 2009.The data are analyzed within the study areas to prepare distribution
zoning and layout plans to show the bulk supply system, source of supply water, points of
the main pipes to service pipes and the position of district meter to measures flow in the
district. The alternative and strategies to manage and overcome water losses at the area
concerned are the developing NRW at these locations. These locations are then analyzed
to distinguish NRW percentages of two adjacent residential areas with different number
of connections and different lengths of pipes.
5
Figure 1.1: The Location of Study Area
6
Figure 1.2 Schematic Drawing for Taman Batu Pahat, BP39
7
Figure 1.3 Schematic Drawing for Taman Makmur, BP40
CHAPTER II
LITERATURE REVIEW
3.1
Introduction
Nowadays, water loss management is a primary concern in many developing
countries. All water networks in the world suffer from water loss and it varies for each
country. The global volume of non-revenue water (NRW) or water losses is unexpected.
Over 32 billion cubic meter of treated water is lost each year through leakage of
distribution network. While 16 billion cubic meter are delivered to the customers but not
invoiced because of theft, poor metering or corruption.[1] These challenges seriously
affect the financial viability of water of water utilities through lost revenues, lost water
resources and increase in cost operation. The volume of water loss depends on the
condition of main and service connections which make up the network. It includes
physical or real losses and apparent or commercial losses.
9
Figure 2.1 “IWA Best Practice” Water Balance and Terminology
2.2
Definition of Non Revenue Water
According to the standard International Water Association (IWA), Non-Revenue
Water (NRW) is defined as the summation of real and apparent losses plus unbilled
authorized consumption.[5] NRW is the total amount of water flowing into the water
supply network from a water treatment plant which is the system input volume minus the
total amount of water that industry and domestic consumers are authorized to use or the
authorized consumption. This is illustrated in Figure 2.1.
NRW = System Input Volume – Billed Authorized Consumption
(Equation 2.1)
10
Equation 2.1 assumes that system input volume has been corrected for any known
errors and system input volume period is corresponding with consistency of the billed
metered consumption period for customer billing records.
2.3
Definition of apparent losses
Apparent losses sometimes called commercial losses, consists of water that is
being consumed from users but not paid for. Some of the cases are water that pass
through the meters but not recorded accurately due to meter errors, meter under
registration, water theft and water accounting errors.
2.3.1
Elements of apparent loss
Initially, commercial losses can be classified into four fundamental elements such
as customer meter inaccuracy, unauthorized consumption, meter reading errors and data
handling and accounting errors.
11
Figure 2.2 Four Pillars of apparent losses
Apparent losses usually count for not more than 4 to 6 percent of authorized
consumption. For example, based on Figure 2.2, inaccurate meter reading may be hidden
and this will implement in estimation on billing system that do not match past billing
data. The four elements are described as follows:
i)
Meter under registration is described by inability to measure flows
accurately, especially the lower flows and this tends to increase with time.
ii)
Water theft by connections of the pipeline without authorization by water
authority through passing or damaging customer meter.
iii)
Water accounting errors are consist error in billing, such as computer
based calculations or estimations that do not reflect actual consumption
values.
12
iv)
Meter errors are due to human error such as inaccurate meter reading and
wrong data volumes.
2.3.2
Inefficiency in customer meter
There are several reasons leading to customer water meters losing their efficiency.
This will lead to reduced sales and therefore reduced revenue. Only a few cases of meter
over-registration. Inaccurate meters can be caused by meter wear and tear, demand
profile or demand type problems. Ageing or abrasion of meter moving parts lead to
under-registration. Moreover, poor water quality may cause sediments to form in the
pipes. These sediments will build up on the internal parts of meters and affect the meter
accuracy by increasing friction losses, which causes the meter to run more slowly, thus
under-register consumption. Improper meter installation also leads to inaccurate data and
billing errors.
2.3.3
Unauthorized consumption
Unauthorized consumption includes illegal connections, meter by passing, illegal
use of hydrants, and poor billing collection systems. Illegal connections involve the
physical connections between the distribution networks without approval of the water
utilities. Commonly illegal connections exist during the installation of new supply
connections or sometimes the user‟s supply is cut off after nonpayment and the customer
cannot afford, or refuse to be reconnected.
13
Meter bypass is used by some users to reduce their water bills through a meter
bypass buried around the meter and this is hard to detect. These types of unauthorized
consumption are usually committed by commercial and industrial premises which diverts
the larger volume that goes through the meter while the rest through the bypass pipe.
Illegally use of fire hydrants to fill tankers normally at night or to provide water
supply to the construction sites. Illegal use of fire hydrant can be detected by high volume
of water used in a short period of time is being used.
Sometimes, connections are made legally but the billing department is not notified
of the new connection, therefore the new user is never billed. These unregistered
customers can be detected during the regular meter reading cycle when diligent meter
readers find meters that are not in their register.
2.3.4
Customer meter inaccuracies
Errors on meter can be described through negligence, aging meters or even
corruption during the process of reading meters and billing customers. Inexperienced
meter readers may misread the meter reading such as misplace a decimal places of the
numbers. Dirty dial, faulty meters and jammed meter can also lead to meter reading
errors.
14
2.4
Definition of real losses
Real losses sometimes known as physical losses or leakage consists of the total
volume of water losses minus commercial losses. Old and poorly constructed pipelines,
inadequate corrosion protection, poorly maintain valves and mechanical damage are some
of the factors contributing to leakage. There are three main components of physical
losses:
i)
Leakage from transmission and distribution mains
ii)
Leakage and overflow from the utility‟s reservoirs and storage tanks
iii)
Leakage on services connection up to the customer‟s meter
The first two types of leakage are usually visible to the public while the other is more
difficult to detect and therefore contribute to a greater volume of physical losses. The first
and second types of leakage are easy to notice and can be repaired relatively quickly.[6]
2.4.1
Elements of real losses
Real loss comprises of leakage from transmission and distribution mains, leakage
and overflow from utility‟s reservoirs and storage tanks, and leakage on service
connections up to the customer‟s meter.
15
2.4.1.1 Leakage from transmission and distribution mains
Leakages occurring from transmission and distribution mains are usually large,
and called pipe burst. Pipe burst causes damage on the street surface due to large amount
of lost water in a short period of time. Water flows over the surfaces frequently damage
the surfaces as well as soil erosion. Such bursts are usually not very serious because of
their large size and visibility, the bursts are reported quickly and water supply can be
shut off and repaired afterwards.
The numbers of leaks can be calculated by using the data from record, on mains
repaired during reporting period usually up to 12 months and estimate an average flow
rate of the leaks. This gives the total annual volume of leakage from mains as follows,
a=bxcxd
(Equation 2.2)
Where a is total annual volume of leakage from mains, b is number of reported
bursts, c is average leak flow rate and d is average leak duration
If no detailed data are available, utility managers can use estimated flow rates
from Table 2.1.
Table 2.1 Flow rates for reported and unreported bursts
Source: IWA Water Loss Task Force
Thus, background losses and excess losses can be estimated. Background losses
are individual event such as small leaks and weeping joints that flow at rates too low for
detection by an active leak detection survey. They are finally detected by chance or after
16
they have worsened to the point that an active leak detection survey can discover them.
Table 2.2 shows background losses from various components of the network with
average infrastructure condition.
Table 2.2 Calculating background losses
Source: IWA Water Loss Task Force
Excess losses consist of the water lost from leak which are not detected and
repaired under the current leakage control policy:
Excess losses = physical losses from water balance –known physical loss components
(Equation 2.3)
If Equation 2.3 gives a negative value, the assumption for real loss component
analysis should be rechecked and corrected. If the data still gives a negative value, this is
indicates that there are faulty data used in the water balance calculation.
2.4.1.2
Leakage and overflow from utility’s reservoirs and storage tanks
Most overflows occur at night when demands are low and therefore it is important
to undertake regular nightly observations of each reservoir. Leakage and overflow from
utility‟s reservoirs and storage tanks are easily quantified. Utility‟s reservoirs and storage
tanks are mainly of concrete and steel construction. Therefore leaks can occur along
17
construction joints and corroded layer of the steel tanks. These observations can be
undertaken via installing data logger which will record reservoir levels automatically at
preset intervals or by manually taken the data at night. Drop test can be conducted to
check leakage that occurred from tanks when the utility closes all inflow and outflow
valves to measures the rate of water level drop and then calculates the volume of water
lost. The test is conducted to ensure water tightness and to reveal leakage. However, to
repair these leakages draining down the reservoir and planning an alternative supply is
required.
2.4.1.3
Leakage on service connections up to the customer’s meter
This kind of leakage is usually difficult to detect but gives the largest volume of
real losses. Volume of leakage from service connections is approximately calculated by
deducting the mains leakage and storage tank leakage from the total volume of real
losses.
2.4.2
Characteristics of leakages
Volume of water lost from leaks and bursts are influenced by time. The longer a
leak runs the greater volume of water lost. Figure 2.3 shows ALR, three key factors in the
amount of water that is lost from an individual leak or burst, where A is awareness, L is
location time and R is repair time.
18
Source: IWA Water Loss Task Force
Figure 2.3 Leak duration and flow of water loss
Source: SAJ Non-revenue water handbook
Figure 2.4 Leak run time and volume of water loss
19
Figure 2.4 shows the different types of leakages have different time of awareness.
Types and locations of bursts for example main or service connection affected the total
run time.
i)
Reported bursts are usually reported by the public or observed by the
water utility staff because of visibility and typically high flow rates and
have short awareness time.
ii)
Unreported bursts are usually non visible and commonly occur at the pipe
line buried underground. They are commonly detected during leak
detection surveys or active leakage control (ALC) and often have a long
period of awareness.
iii)
Background leakage mostly occurred at joints and connections. Flow rates
too small to be detected and cause difficult to be detect and repair.
2.4.3
Types of Leakage
There are many different types of infrastructure used in a distribution system as
well as many different types of leaks occurring in a distribution system.
2.4.3.1 Crack
This term is used to describe a pipe failure mechanism occurring as
circumferential or longitudinal failure that usually results from pipe deterioration or
ground movement. They may go undetected for some time and eventually deteriorate to
become a reported main break or fracture. The quality of the leak noise depends on
factors such as pressure and pipe material, but usually is distinct and of high audible
frequency.
20
2.4.3.2 Pinhole
Pinholes leaks are small circular failures in a pipeline usually caused by corrosion
or stress by stones after poor backfill procedure during installation. Steel pipe installed in
a corrosive environment without proper corrosion protection is particularly susceptible to
the development of pinhole leaks, which can develop very quickly. As short as several
months time in extremely corrosive environments.
2.4.3.3 Seepage
Commonly, Asbestos cement pipes deteriorated where the pipe wall becomes
semi porous and water escapes slowly. These types of leaks are extremely difficult to
locate as leak noise is minimal. Asbestos cement pipes normally classified as
undetectable background leakage. Losses caused by seepage can be minimized by use of
pressure reduction or infrastructure replacement.
2.4.3.4 Pipe Joint Leaks
These are common points of leakage, particularly on older cast iron and AC pipes
where the caulking or joint gasket deteriorates over time. Many older couplings are not
corrosion protected and therefore deteriorated long before pipe itself. When ground
movement occurs, pipe joints bear most of the strain, often resulting in leakage and
eventually a fracture.
21
2.4.4
Management Tools for Real losses Reduction
2.4.4.1 Unavoidable Annual Real Losses (UARL)
The elements such as active leakage control (ALC) and repair activity can
considered to be revenue items and would therefore be considered in the evaluation of the
short run economic level leakage (ELL), whereas pressure management and mains
rehabilition would require an investment decision, and would therefore be considered in
the evaluation of the long run ELL.
Source: SAJ Non-revenue water handbook
Figure 2.5 The Four Basics Methods of Managing Real Losses
Real losses cannot be eliminated totally. The lowest achievable annual volume of
real losses for well maintained and well-managed systems is known as unavoidable
annual real losses (UARL). Figure 2.5 shows the relationship between current annual real
22
losses (CARL) from an IWA water balance represented by a large rectangle and UARL
the small rectangle. The four pillars of a leakage management strategy include pressure
management, active leakage control, assets management and repairing (the four arrows)
to control the real losses but at the current operating pressure cannot be reduced any
further than the UARL. CARL tends to increase as the distribution network ages. But the
appropriate combination of four components can limit the rate of increase of real losses.
Data for this assessment are the number of service connections, the length of main,
private pipes between the streets and customer meters and the average operating
pressures.
Source: Ranhill
Figure 2.6: Typical losses from a water supply system
Figure 2.6 shows the difference between physical losses and apparent losses from a
distribution networks.
23
2.4.5
Active leakage control (ALC)
The reduction and control of water losses become more vital in this age when
water demand is high. Active leakage control can best be described as a proactive
strategy to reduce water loss by the detection of non visible leaks and their prompt
repaired by highly trained engineers and technicians using specialized equipment.[8] The
concept of monitoring of flows and pressures of a water network in a small area is
commonly called District Meter Areas (DMAs). Unreported Bursts and leaks are now
established to determine the leak location activities. The faster the operator can analyze
DMA flow data, the faster bursts or leaks can be located.
There are many points in a distribution network where leakage might occur and
the location they are best to monitor. Figure 2.7 shows the strategic points to install data
logger.
Source: Ranhill
Figure 2.7: A typical distribution network
24
2.5
Introduction to District Meter Area (DMA)
DMA management is used to determine the level of leakage within a defined area
of the water network. The concept of DMA monitoring is to measure flow into a discrete
area with a defined boundary and observe typical variation in flow. Current levels of
leakage and priorities of the leakage location activities are enabled by the establishment
of a DMA. The presence of new bursts can be identified by monitoring flows in DMAs so
that the leakage can be maintained at optimum level.
The network can be divided into several DMA and the accurate bulk of water
meter is installed at the entry point of each districts. The sum of the flow total for each
district is recorded should equal to the quantity of water measured at the outlet from
consumer. DMA is relevant especially at residential area where the night flow is expected
to be zero [4]. So the night flow for each district can be regularly monitored and the
presence of unreported burst and leakage can be identified and located. Besides, the
pressure in district can be monitored so that the network is operated at optimum level of
pressure. Figure 2.8 shows a typical DMA design, including the monitoring hierarchy
upstream and downstream of the DMA.
2.5.1
Figure 2.8: A typical DMA design
Criteria and process of DMA establishment
25
There are several criteria that should be taken into account to create a preliminary
DMA design [3]:
i.
Size of DMA. The ideal size of zone consists between 1000 and 2500 the
number of connections depends on density of population. The smaller the
areas, the more manageable to monitor and maintain. This is because the
smaller the size of a DMA the faster the leakage will be identified. For
example, if the DMA is larger than 1000 properties or service connection,
this becomes difficult to discriminate small leaks from customer
consumption volume.
ii.
Number of valves that must be closed to isolate the DMA. It is essential
to close valves to isolate a certain area and install flow meters. This
process can affect the system‟s pressures, within the particular DMA as
well as its surrounding areas.
iii.
Number of flow meters to measure inflows and outflows. It is much
preferable for one district zone to have one point of supply. The fewer
meter required, the lower the initial cost of establishment.
iv.
Water quality consideration. Water quality should be monitored prior to
and after the installation of DMA. Poor water quality may occur after
creating a DMA. This is because creating a DMA will involve closing
valve to permanently form a boundary which creates more dead ends than
would normally be found in fully open system. The problem can be
alleviated by a flushing program.
v.
Ground-level variations and thus pressures within the DMA. The
flatter the area, the more stable the pressures and the easier to establish
pressure controls.
26
vi.
Pressure. The pressure reduction should be in range of 10 psi (7mH) to 15
psi (11mH). It is much preferable zone that has at least 20mH night
pressure at the target point. Target point usually the highest or furthest
position from the inlet meter.
vii.
Topographic features. Easily visible topographic features that can serve
as boundaries for DMA such as rivers, drainage channels, railroads,
highways, etc.
2.5.2
Initial DMA installation and testing
In order to verify the integrity of the DMA and gain the data that necessary for the
DMA chamber design, the DMA needs to be set temporarily and gather the field
measurement as the initial design phase of DMA. The DMA needs to be set up by closing
all identified boundary valves and verifying the status of already closed valves. The
DMA is supplied through the selected feeder mains to be monitored by using temporary
flow meters or clamp on ultrasonic flow meters.
2.5.3
DMA meter selection
The selection and installation of the DMA meters are the key components when
designing and creating new DMA. There are several components that related on selecting
the DMA meter such as the size of meter, ability of meter to record the accurately
27
maximum and minimum flow rates and the necessity to meet demand and fire flow
requirements.
The selection of meter type and size depends upon:
2.5.4
i.
Size of main pipe
ii.
Flow range
iii.
Head loss at peak flows
iv.
Reverse flow requirements
v.
Accuracy and repeatability
vi.
Data communication requirements
vii.
Cost of meter
viii.
Water utility preference
District Meter Area installation procedure
Following the initial design phase, the DMA need to be set temporarily with
identification from network plan to establishment of district zone. The DMA has to be set
up by closing all identified valves and verifying the status of already closed valves.
Ensure that water is not entering the area from any source when the main feeder of water
supply is closed. The pressure within a zone is supposedly giving zero reading due to
absence of water entering the boundary area via boundary valve. This is called by zero
pressure test.
After proving is successful, boundary valve is confirmed 100 percent closed and
spraying with red in color. Next step is by installation of temporary flow meter at the
main feeder. The temporary flow meter using may an electromagnetic insertion flow
meter or clamp on ultrasonic flow meter. Next integrity of the DMA boundaries is by
conducting pressure drop test to analyze the effective reduction in pressure in the area.
28
During this test the pressure is dropped within the DMA in various steps by operating the
valve. The test should be conducted during the minimum night time flow between 2 and 4
am in order to avoid customer consumption disruption that would generate complaints.
During this period when there are maximum of total flow occurs on DMA meter, as the
result leakage occurs in this area.
Once the integrity of the DMA has been confirmed it is necessary to measure the
total inflow to the DMA over several days to calculate existing volume of leakage and to
estimate the future leakage target volumes. If the water supply is insufficiently provided
enough capacity of fire flow emergencies in this area, then it is necessary to redesign the
DMA and either change the boundaries or to include an additional feeder main in the
design.
2.5.5
DMA data monitoring
The selection of DMA monitoring and data transfer capabilities influencing the
optimum cost and volume of leakage is determined in short period of time. The cost of
water is relatively low hence it is very likely that there no financial incentive in detecting
small leakage instantly. So it is not necessary to have real time transmission of DMA
data. The data from DMA might be transferred once a week. The minimum night flow
only reach the level of intervention after a few days when several of leaks occurred in
DMA.
However in the Johor state, Syarikat Air Johor (SAJ) considers data transmission
through GSM telemetry as monitoring the DMA flow and pressure data is transmitted
through global system for mobile communication (GSM) short message service (SMS).
SAJ used the loggers that able to transmit the recorded and logged flow and pressure
29
values on a regular basis using SMS. These loggers can transmit the data to a host
computer on a daily, weekly, or monthly basis. The cost of installation for this option is
very low.
2.5.6
DMA Data Analysis
The minimum night time flows in urban areas usually occur between 2.00 and
4.00 am. This flow value is a meaningful data to obtain the leakage rate in DMA.
Leakage occurs as the maximum percentages of the total inflow during this period of time
while authorized consumption is at minimum flow rate. Minimum net night time flow or
net night flow (NNF) is obtained by subtracting the legitimate night consumption from
minimum night flow.
NNF = MNF – legitimate nighttime consumption
(Equation 2.4)
The NNF is composed of the real losses from the distribution network and the
service connection piping between the water main and the customer meter.
To conduct a MNF analysis, the following data is also required for the inflow
measurement and pressure management at the inlet point:
i.
Length of mains
ii.
Number of service connections
iii.
Number of household properties
iv.
Number and types of non household properties
v.
Legitimate nighttime consumption (can be estimated or obtained by measuring a
sample of customers and inferring the entire population)
30
Legitimate night consumption is carried out by three components:
i.
Exceptional night use: Some users can be large significant in using the water
during nighttime period due to the nature of their business process such as public,
commercial, industrial, and agricultural customer. These customers need to have
discussion to the local operational staff and have an exceptional night use on
getting MNF data during the time they operate their business in order to accurate
in deduct this component of legitimate consumption from the total inflow.
ii.
Non household night use: Exceptional night users may consume some water at
night such as for automatic flushing system. Some allowances for this night
consumption has been made. This is made by making estimates based on the type
of industry and typical publish consumption volumes for certain users.
iii.
Household night use: Household night consumers also consume some water
during the minimum night time flow period. This is due to toilet flushing,
automatic washing machines and outdoor landscape irrigation. Household night or
residential consumers that using night water can be determined by gathering data
of night customer consumption measurement through manually or automatic
meter readings during the minimum night time consumption period.
2.6
Step Test Method
Step testing involves isolating sections of the water into small zones and
measuring the supply into the zone. This opften done on a temporary basis and portable
flow meters are used to measure flow into the zone. When undertaking step testing, it is
31
very important to execute the test in a manner that does not cause interruption to
customer supply. For this reason step test is usually carried out at night when customer
consumption is at a minimum. Step test operations typically start at 11.30 or 12.00 pm,
with the fixing of the data logger and pulse unit to the flow meter and opening or closing
of valves at the flow meter. Therefore all water is supplied to the area through flow
meter.Step Test is carried out when a decision to proceed with leakage detection
operation in particular area has been made. It is advisable to repair any visible leaks in the
area.
Step tests aims to:
i.
Identify quickly the problematic areas when high leakage is occurred.
ii.
Adopt an economic approach in leak detection
iii.
Shorten the leak localization time
Two functions of step tests are:
i.
Isolation of leakage to individual pipelines or sub-areas of a Zone, resulting in a
reduction in the amount of leak detection work.
ii.
Quantification of the leakage
The area flow meter is used with data logger equipment to record water flows
during the test which is carried out at night when the minimum night flow
occurred. All of valves and boundary valves are fully closed. Each valve closure
shuts off a section of the supply system or length of pipeline, eliminating flows of
water for the section.
Step valves in particular should be sounded with care on closure as follows:
32
i.
Close valve at scheduled time.
ii.
Sound valve. If water is passing, partly open the valve and re-close.( This may
flush out debris preventing the valve to close properly). Sound valve again. If
water is still passing, note down on the program sheet.
iii.
If water is not passing with the valve closed, partly open the valve again and
sound the valve. Note down wheter the valve can now be heard to be passing or
not. Re-closed the valve and re-check that no noise can be heard when close.
2.7
The 2008 Annual Water Balance for Johor
Table 2.3 shows the annual water balance in Johor for the year of 2008, currently
in Johor state, 31.0 % of the water supply is non revenue water. The main contributor to
this water loss is real loss which is 23.8 % is dealing with leakage of the pipelines
system. It was determined NRW was 161,899,016.88 Ml/Annum. Of the total NRW, the
physical losses were estimated at 24.7 % and the non physical losses at 6.3%. In order to
reduce the amount of NRW, some of strategies can bring immediate cost savings in term
of production cost.
33
Table 2.3: The 2008 Annual Water Balance for Johor
Authorised
Consumption
359854137.11
69.0%
System Input
Volume
521621853.39
100%
Billed
Authorized
Consumption
69.0%
Unbilled
Authorized
Consumption
0.0%
Apparent
Losses
6.30%
Water Losses
161 767,716
31.0%
Real Losses
24.70%
Billed Metered Consumption
67.80%
Billed Unmetered Consumption
1.19%
Revenue Water
69.0%
Unbilled Metered Consumption
0%
Unbilled unmetered
Consumption
0.03%tp
Unauthorized Consumption
Not identified
Billing & Customer Meter
Inaccuracy
Not identify
Losses On Overflow at Storage
Tank
0.08%
Losses On Transmission and
Distribution Main
0.90%
Non-Revenue
Water
31.0%
Background & Burst Leakage,
Major & Minor Leaks
23.80%
Source: Syarikat Air Johor 2008
2.8
Percentage of Non Revenue Water (%)
Table 2.4 shows the percentage of NRW for each state in Malaysia in the year of
2005 and 2006. In the year of 2005, NRW in Sabah is the highest percentage followed by
Negeri Sembilan which is 57.20 % and 53.00 % respectively. After a year, the amount of
water loss in Sabah decreased about 0.2 % and increasing amount of NRW in Negeri
Sembilan with 60.10 %. Pulau Pinang shows the least amount of NRW for 2005 and
34
2006 which is 19.40% and 18.60% respectively. Meanwhile, Johor state shows the
average of NRW among others and record about 35.50 in the year 2005 and 32.46 in the
year 2006.
Table 2.4 Percentage of Non Revenue Water (%)
WATER SUPPLY
Non-Revenue Water (%)
AUTHORITY
JOHOR
KEDAH
KELANTAN
MELAKA
N.SEMBILAN
PAHANG
PERAK
PERLIS
P.PINANG
SABAH
SARAWAK
SELANGOR
TERENGGANU
W.P LABUAN
NATIONAL AVERAGE
2005
35.50
43.80
40.00
28.80
53.00
49.70
30.60
36.30
19.40
57.20
24.70
38.40
34.70
24.00
37.70
Source: Malaysia Water Industry Guide 2007
2006
32.46
45.00
44.40
27.00
60.10
46.40
30.70
35.54
18.60
57.00
32.00
36.60
31.50
36.00
37.70
CHAPTER III
METHODOLOGY
3.2
Introduction
District Meter Area method is being used in the implementation of controlling
non-revenue water for estimating of water losses in certain period of time such as three
months, six months or twelve months. To undertake any water system audit and properly
identify where volumes of losses are occurred and the magnitude of the loss it is
necessary to collect data which are accurate, standardized, organized and accountable.
Commonly, the large volumes of data are collected. Existing data and information are
collected from SAJ Holdings Sdn Bhd for analysis.
3.2
Study Flow Process
Figure 3.1 shows the procedure flow to obtain comprehensive assessment.
36
1. Identifying the problems of Non-Revenue Water around the world. State the
problems of NRW and find the most critical region of NRW at Johor.
2. Gathering all of information related to Non-Revenue Water such as the factors
contributing, effects and steps to be taken to reduce NRW. Information is
obtained from primary and secondary references.
3. Design the study such as created the title, set the objectives, scopes of study
and so on.
4. Identify the instrument to be used. This assessment required the data
collection from water utilities.
5. Observation of the study area in Batu Pahat, Johor and interviewing water
utilities at Batu Pahat regarding NRW components.
6. After made decisions, I choose two of District Meter Area at Batu Pahat as my
study areas.
7. Gathering important data of study areas for analysis such as minimum night
flow, average flow, water provided, water consumption and schematic
drawing of the areas.
8. Visiting the study areas with water utilities and visually collect reading from
the water meters for each premise.
9. Data are analysed using two types of methods such as Step test method and
Water audit method.
10. After done analyse for one District Meter Area, for another District Meter
Area the steps carry out is same as before.
37
11. Finally, discussion, conclusion and recommendation are carried out from this
assessment.
Identify Problems
Gathering information,
primary and secondary
references
Identify instruments being
used
Study Design
PSM 1
Observation and Interviews
water utilities
Gathering Data and Information
from study areas
Site Visit
Analysis Data
Discussions, Recommendations and
Conclusions
Figure 3.1: Procedure Flow
PSM 2
38
3.3
Case Study
The traditional approach to leakage control has been a passive one, whereby the
leak is repaired only when it becomes visible. The development of acoustic instruments
has significantly improved the situation such as by allowing invisible leaks to be located
as well. But the application of such instruments is ineffective for a large water network.
The solution is a permanent leakage control system whereby the network is divided into
small area, more manageable area which is District Metered Areas (DMA). DMA enables
to manage the system effectively in term of controlling NRW. By installation of flow
meters, it is possible to regularly quantify the leakage level in each DMA so that the
leakage location activity is always directed to the worst parts of the network.
Parit Raja Water Supply System (WSS) is supplying water to the studied areas.
Parit Raja is located at Batu Pahat Johor, western of Peninsular Malaysia. Based on
Water Supply System drawing, Parit Raja WSS serves 49 DMA. Two residential areas
from single WSS were selected to implement this research. These two areas are Taman
Batu Pahat, BP39 and Taman Makmur, BP40. Both studied areas implementing DMA
methods to control high level of NRW. (Refer to Appendix a)
In determination of NRW using DMA compliance, two areas are selected which is
BP39, Taman Batu Pahat and BP40, Taman Makmur. Schematic plan for each area are
retrieved from Control Unit of SAJ Holdings Sdn. Bhd. at Batu Pahat.
Taman Makmur‟s total of connections is higher compared to Taman Batu Pahat
which is 1192 connections and 610 connections. Moreover, the total tariff installation for
each area is identified. There are 478 connections mostly consisting single-storey houses
and 131 shop houses in BP39 while there are 959 numbers of houses, 231 shop houses
and 1 government holding in BP40. Length of the main pipe for BP39 is 5.4 km while for
BP40 is 8.2 km. Types of pipe installation for both zones are Ductile Iron and Asbestos
39
Cement. For BP39 the main type of pipe is Ductile Iron while for BP40 is Asbestos
Cement pipe.
3.4
Data Acquisition and calculation
Data using for this assessment are for one year data from January to December
2009.Data that required for analysis is total water demand, water consumption, pressure
and Net Night Flow (NNF) which is determined by subtracting the Legitimate Night
Flow (LNF) from the Minimum Night Flow (MNF). The MNF is the lowest flow into the
DMA over a 24 hour period, which generally occur at night when the most users are
inactive. This MNF can be measured directly from data logger or the flow graph while
LNF is calculated by measuring the hourly night flow for all non domestic demand and a
portion of domestic meter within the DMA. LNF test will be conducted for a two hour
interval period between 2:00 am and 4:00 am to calculate the average LNF.
Billing data and the customer water consumption data for Taman Batu Pahat and
Taman Makmur area are determined. The justification for use of customer meters in
water utilities has been periodically obtain measures of customer consumption that serve
as the basis for billing. Meters are usually read by manual meter reading or automatic
meter reading. Figure 3.2 shows water utility manually read customer meter. Water
utilities of SAJ Holdings Sdn Bhd obtained water consumption for both areas by using
manual meter reading with meter readers visiting individual customer premises to
visually collect readings. Some of the reading attempt is unsuccessful in obtaining the
actual meter reading, most of the water utilities bill customers using an estimated volume
that is calculated based on the customer‟s recent consumption history.
40
Figure 3.2: water utility manually read customer meter
Pressure of T factor test data is collected and calculated for both areas using step
testing. Step testing is usually carried out at night when customer consumption is at a
minimum. Height, low and average pressure is obtained for every 2 hours out of 24 hours
and also for the leakage index. In addition, historic burst data for each area is collected
and the numbers of register connection or tagged billed consumers and estimate numbers
of untagged billed consumers also collected.
All of the data are being analyzed within the study area. Data are being used is
secondary data which is obtained from SAJ Holdings and Ranhill Water Services at Batu
Pahat Johor.
CHAPTER IV
RESULTS AND DISCUSSIONS
4.1
RESULTS OF NRW
There are two selected areas of NRW zones at Taman Batu Pahat, BP 39 and
Taman Makmur, BP 40. Those areas are adjacent to each other with the same time of
development and shares water supply system from the same balancing reservoir, Bukit
Soga West 2. Taman Batu Pahat and Taman Makmur are in the central zone of Batu
Pahat. The population of Taman Batu Pahat is less than that of Taman Makmur, which is
approximately 700 and 1200 respectively. Both areas are residential areas that include
rows of shop houses. Most of the houses at those areas are single-story terraced houses.
After preliminary investigation of the areas, Taman Batu Pahat shows the highest
amount of abandoned houses compared to Taman Makmur which is seen to be more
developed. Nevertheless, those areas detailed network properties are shown in Table 4.1.
42
Table 4.1: Network properties for each zone
DMZ
Type of
Pipe
Ductile Iron
BP39
Asbestos
Cement
BP40
Length of
Mains (km)
Network
Connection
1
2
3
Total
LNF
(l/s)
T factor
5.4
478
131
0
609
0.45
19.08
8.2
959
231
1
1191
2.54
11.23
*Note: Connection 1: Residential house ; Connection 2: Shop houses; Connection 3:
Government building
4.2
‘T’ factor for Taman Batu Pahat Area BP39
Ranhill Water Services,(RWS) introduced the calculation of a key measurement
which is T factor for Batu Pahat areas. T factor is significant to the precise magnitude of
leakage. T factor is a correction factor computed by adding the total leakage index,
divided by the highest leakage index, and then multiplied by the two-hour interval
reading:
T= (Total Leakage Index /highest Leakage Index) x 2 hours
(Equation 4.1)
The first step in measuring T factor is to identify the highest and lowest point in
the DMA and install pressure data logger at both points. Then activate data logger to
obtain 24-hours pressure data. Lastly, the T factor is computed.
43
Table 4.2: Average pressure and leakage index for area BP39
Period
0-2 am
2-4
4-6
6-8
8-10
10-12noon
12-14
14-16
16-18
18-20
20-22
22-24
High Pressure
(m)
43.4
45.31
45.38
28.87
33.61
33.68
33.82
34.71
34.72
30.50
35.87
40.59
Low Pressure
(m)
41.27
42.97
42.77
28.66
33.77
34.01
35.51
35.11
34.36
31.06
36.16
38.12
Ave. Pressure
(m)
42.33
44.14
44.08
28.77
33.69
33.85
34.67
34.91
34.54
30.78
36.02
39.36
Total
Leakage Index
29.22
31.09 (B)
31.05
18.49
22.46
22.56
23.45
23.60
23.40
20.52
24.00
26.74
296.58(A)
(Source: Ranhill Water Services Sdn Bhd)
Referring to the Table 4.2, average pressure data is obtained by summation of
high pressure and low pressure and divided by 2.The highest average pressure will give
the value of highest leakage index. Table 4.3 shows the relationship between leakage (net
night flow) and pressure
Leakage index for the period, B = 31.09
From equation 4.1,
T = (A/B) x 2 hours
= (296.58/31.09) x 2
=19.08 hours
Therefore, T factor for BP39 is 19.08 hours.
44
Table 4.3: Relationship between leakage (net night flow) and pressure
AVERAGE AREA
LEAKAGE INDEX
NIGHT PRESSURE
10
6
11
7
12
7.5
13
8
14
8.5
15
9
16
10
17
10.5
18
11
19
11.5
20
12
21
13
22
13.5
23
14
24
15
25
16
26
16.5
27
17
28
18
29
19
30
20
31
20.5
32
21
33
22
34
23
35
23.5
36
24
37
25
38
26
39
26.5
40
27
(Source: Ranhill Water Services Sdn Bhd)
AVERAGE AREA
NIGHT PRESSURE
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
LEAKAGE INDEX
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
45
Table 4.4: Average pressure and leakage index for Taman Makmur BP40
Period
0-2 am
2-4
4-6
6-8
8-10
10-12noon
12-14
14-16
16-18
18-20
20-22
22-24
Height Pressure
(m)
38
42
22
22
18
20
16
20
16
10
18
28
Low Pressure
(m)
36
40
20
20
16
18
14
18
14
8
16
26
Ave. Pressure
(m)
37
41
21
21
17
19
15
19
15
9
17
27
Total
Leakage Index
23.75
27.50 (B)
12.02
12.02
9.35
11.00
8.12
11.00
8.12
4.67
9.35
17.50
154.40 (A)
(Source: Ranhill Water Services Sdn Bhd)
Table 4.3 indicates leakage index and Table 4.4 shows the average pressure and
leakage index of Taman Makmur, for the calculation of T factor. T factor maximum
value is 24 hours. T factor is significant to describe how long the pipe will obtain
leakage.
Leakage index for the period, B = 27.5
From equation 4.1,
T = (A/B) x 2 hours
= (154.40/27.50) x 2
= 11.23 hours
Therefore T factor for BP40 is 11.23 hours.
46
4.3
Leakage Percentage using Step Test Method
Table 4.5: Leakage percentage of BP39 and BP40 for 2009
DMZ
TMN.
BATU
PAHAT
BP39
TMN.
MAKMUR
BP40
T
Month
MNF
Jan
Feb
Mac
Apr
May
Jun
July
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mac
Apr
May
Jun
July
Aug
Sep
Oct
Nov
Dec
3.84
3.95
4.16
4.16
4.16
4.16
0.85
1.13
0.57
0.69
0.85
0.85
2.90
3.41
3.41
3.41
3.41
3.41
7.88
4.32
3.55
3.35
2.99
2.99
NNF
(l/s)
3.39
3.50
3.71
3.71
3.71
3.71
0.40
0.68
0.12
0.24
0.40
0.40
0.36
0.87
0.87
0.87
0.87
0.87
5.34
1.78
1.01
0.81
0.45
0.45
NNF
(l/c/hr)
20.00
20.66
21.90
21.90
21.90
21.90
2.36
4.01
0.71
1.42
2.36
2.36
1.09
2.63
2.63
2.63
2.63
2.63
16.14
5.38
3.05
2.45
1.36
1.36
Leakage
(m3/day)
232.78
240.46
254.89
254.89
254.89
254.89
27.47
46.67
8.26
16.53
27.47
27.47
14.59
35.21
35.21
35.21
35.21
35.21
216.07
72.02
40.83
32.80
18.21
18.21
Leakage
(%)
33.25
33.68
34.77
34.77
34.77
34.77
5.86
9.95
1.89
3.52
6.09
6.33
1.55
3.80
3.80
3.80
3.80
3.80
20.56
6.90
4.20
3.12
2.00
2.10
Ave.
Leakage
19.97 %
4.95 %
able 4.5 shows the Minimum Night Flow (MNF), Net Night Flow (NNF), and the
leakage percentage for the whole year of 2009 for BP39 and BP40 zones. In order to
obtain the value of the data, Step Tests have conducted. Average leakage for BP39 is
higher compared to BP40 which is 19.97% and 4.95% respectively. The computation of
leakage percentage is determined by the sample calculation in Table 4.6.
47
Table 4.6: Sample Computation of Leakage Percentage on January on Taman Batu Pahat,
BP39
Item
Computation
Unit
Output
l/s
3.84
A
Minimum Night Flow to zone, MNF
( base 24 hours graph of MNF)
B
Minimum Night Flow (convert item A to l/c/h)
MNF= (MNF/C) x 3600
= (3.84/609) x 3600
= 22.70
l/c/h
22.70
C
Legitimate Night Flow, LNF
(From Field Reading)
l/c/h
2.66
D
Current Net Night Flow, NNF
NNF= MNF (item B)-LNF(item C)
=22.70-2.66
=20.04
l/c/h
20.04
E
Total Leakage in Zone, L
L= (NNF x T factor x C)/1000
=(20.04 x 19.08 x 609)/ 1000
=232.86
Where
NNF=Net Night Flow (from Item D)
T=Time Factor
C=No of connections
M3/d
232.86
F
Total Flow to Zone, F
(Based on 24-hours graph of MNF)
M3/d
700
G
Current Leakage Percentage, CLP
CLP = L/F x 100
=232.86/700 x 100
=33.25
%
33.25
48
Minimum Night Flow,MNF (l/s)
9
8
Before Proving
After Proving
7
6
Mean MNF BP40=3.44
5
4
3
BP39
2
Mean MNF BP39= 0.81
1
0
Jan
BP40
Feb Mac Apr May Jun July Aug Sep Oct Nov Dec
BP39 3.84 3.95 4.16 4.16 4.16 4.16 0.85 1.13 0.57 0.69 0.85 0.85
BP40 2.9 3.41 3.41 3.41 3.41 3.41 7.88 4.32 3.55 3.35 2.99 2.99
Month
Figure 4.1: Minimum Night Flow for BP39 and BP40
Figure 4.1 shows the Minimum Night Flow (MNF), for Taman Batu Pahat, BP39
and Taman Makmur from January 2009 to December 2009. Minimum Night Flow of
BP39 and BP40 for the first six month are constantly flat with slight increase of 4.16 l/s
and 3.41 l/s respectively. On July, Minimum Night Flow for BP39 decreases abruptly
from 4.16 l/s on June to 0.85 l/s on July. In August till the end of the year, Minimum
Night Flow values are reduced gradually. While for BP 40, there is a rapid increase of
Minimum Night Flow value which is 7.88 l/s and drops to 4.32 in August and
continuously decrease till December. After proving, Minimum Night Flow mean is 0.81
l/s and 3.44 l/s for BP 39 and BP 40 respectively.
49
4.4
Non Revenue Water percentage using Water Audit Method
Table 4.7: Non Revenue Water using Water audit Method
a) Taman Batu Pahat BP39
DMZ
Month
Ave. Flow
(m3/day)
Water
Consumption
(m3/day)
Taman
Batu
Pahat
BP39
Jan
Feb
Mac
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
700
714
733
733
733
733
469
469
437
469
451
434
408
403
392
401
399
407
437
367
393
373
382
381
NRW
Volume
(m3/day)
NRW %
Ave.
NRW
(after
proving)
292
311
341
332
334
326
32
102
44
96
69
53
41.7
43.6
46.5
45.9
45.6
44.5
6.8
21.7
10.1
20.5
15.3
12.2
15.96%
b)Taman Makmur BP40
DMZ
Month
Ave. Flow
(m3/day)
Water
Consumption
(m3/day)
Taman
Makmur
BP40
Jan
Feb
Mac
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
941
926
926
926
926
926
1051
1051
971
1051
910
888
802
803
747
782
759
781
819
745
766
784
791
820
NRW
Volume
(m3/day)
NRW %
Ave.
NRW
(after
proving)
139
123
179
144
167
145
232
306
205
267
119
68
14.8
13.3
19.3
15.6
18.0
15.7
22.1
29.1
21.1
25.4
13.1
7.7
19.28%
50
Referring to Table 4.7, Non Revenue Water (NRW) for BP39 and BP40 zones are
obtained by using Water audit method. In this case, water production from meter flow
logger and water consumption data are extracted from customers billing system. The
formula for determine NRW is:
Non Revenue Water percentage = Water Production –Water Consumption) x 100
Water Production
(Equation 4.2)
Referring Table 4.7, take a sample for BP39 on January 2009. Average flow for
this area is 700 m3/day and was obtained from meter flow logger at the entry point of the
area. Average flow is significant the water production for such area while water
consumption is 408 m3/day in January. Water consumption is the water used by the
customer in the same particular area.
From equation 4.2,
Percentage of NRW
= (Water Production –Water Consumption) x100 %
Water Production
= (700 m3/day -408 m3/day) x 100 %
700 m3/day
=
41.7 %
Average NRW for BP39 is higher compare to BP40 which is 26.2 % and 17.9 %
respectively.
51
Average Flow (m3/day)
1200
Mean Ave. Flow BP40=974.2
1000
800
After Proving
600
BP39
Before Proving
BP40
400
Mean Ave. Flow BP39= 452
200
0
Jan Feb
Ma
Ma
Apr
Jun July Aug Sep Oct Nov Dec
c
y
BP39 700 714 733 733 733 733 469 469 437 469 451 434
BP40 941 926 926 926 926 926 1051 1051 971 1051 910 888
Month
Figure 4.2: Water production of Taman Batu Pahat, Bp39 and Taman Makmur, BP40
Figure 4.2 shows the pattern of water production among two adjacent areas from
January to December 2009. For BP 39, average flow from January to June is gradually
flat and same goes to BP40. In July, average flow for BP39 is decreased rapidly and
continued to be flat until the end of the year. On the other hand, on July, BP 40 is giving
the high amount of water production compared to six month before and having almost
constant amount of water production until December. After proving, mean average flow
for BP39 is 452 m3/day while for BP40 is 974.2 m3/day
Generally, almost 80 % of the leakage in contributed to Nonrevenue Water
(NRW) and the rest is due to apparent losses. By using step test method, assume leakage
percentage is assumed as NRW. The comparison of NRW between Step Test method and
Water Audit method is conducted.
Percentage (%)
52
50
45
40
35
30
25
20
15
10
5
0
After Proving
Mean NRW=15.96%
Before Proving
Leakage
NRW
Mean Leak=5.55%
Jan Feb Mac Apr May Jun July Aug Sep Oct Nov Dec
Leakage 33.3 33.7 34.8 34.8 34.8 34.8 5.86 9.95 1.89 3.52 6.09 6.33
NRW
41.7 43.6 46.5 45.9 45.6 44.5 6.8 21.7 10.1 20.5 15.3 12.2
Month
Figure 4.3: Leakage and NRW percentages for Taman Batu Pahat, BP39
From Figure 4.3, Step Test method and Water Audit method have almost the
same pattern with leakage percentage smaller than NRW percentage. In July, NRW for
this area is off peak with lower percentage for both methods due to a proving exercise
(zero pressure test) for this area. As a result, the NRW and leakage for the preceding
months indicate marked reduction of 15.96%, 5.55% and 19.2%, 3.3% for BP39 and
BP40 respectively.
53
35
Before Proving
After Proving
Percentage (%)
30
Mean NRW=19.3%
25
20
15
Leakage
10
5
0
Jan Feb Mac Apr
Leakage 1.55 3.8
NRW
NRW
Mean Leak =3.3%
3.8
3.8
Ma
y
Jun July Aug Sep Oct Nov Dec
3.8
3.8 20.6 6.9
4.2 3.12
2
2.1
14.8 13.3 19.3 15.6 18 15.7 22.1 29.1 21.1 25.4 13.1 7.7
Month
Figure 4.4: Leakage and NRW percentages for Taman Makmur, BP40
Figure 4.4 shows the percentages of leakage and NRW for Taman Makmur. In
July, this area experienced peak percentages of leakage and NRW due to a reported pipe
burst in this area. Consequently of Step Test method, the graph of leakage percentage
indicates gradual constant for certain period of time compared to Water Audit which that
shows unstable percentage of NRW for each month. As a result, mean NRW percentage
is 19.3% and mean leakage percentage is 3.3 %.
54
4.5
Discussions
From the analysis of Step Test and Water Audit methods, both indicates different
results of NRW and leakage percentages. Step Test method shows lower leakage
percentage compared to Water Audit, which has shows higher percentage of NRW. This
is due to different methods of calculation and different properties for both areas. Step
Test method depends on MNF, NNF and LNF variables while Water Audit method
depends on average flows and water consumptions. Both methods have different time and
duration on interval.
Both methods have advantages and disadvantages. Step test aims to identify
quickly the problematic areas such as high leaks or burst due to higher amount of MNF.
MNF measurement should be taken for a minimum of 24 hours and send to utilities via
telemetry. In the other hand, Step tests shorten the leak localization time in locating the
elusive and non surface leaks. To obtain precise and accurate data in step test method,
utilities need to have skill in conducting the test. Step tests only aim at leakage detection
and not considering other factors of NRW such as apparent losses, illegal use or
inaccuracy of meter reading.
On the other hand, water audit method is an easy method to obtain NRW but
taken a long period of time and extracting the billing data from consumers for every
month. This method will contribute to the inaccuracy of meter readings by utilities and
faulty meter. Average flow is measured at any supply point to measure demand from
consumers. Consumption data is necessary to adjust average flow to supply water to
consumer with sufficient amount. Unfortunately, water audit method is such a slow
method for leak detection and control.
55
50
45
Mean NRW BP39 =15.96%
40
NRW %
35
Mean NRW BP40 = 19.28%
30
25
20
BP39
15
BP40
10
5
0
After Proving
Before Proving
Jan
Feb Mac Apr May Jun
July Aug Sep Oct Nov Dec
BP39 41.7 43.6 46.5 45.9 45.6 44.5 6.8 21.7 10.1 20.5 15.3 12.2
BP40 14.8 13.3 19.3 15.6
18
15.7 22.1 29.1 21.1 25.4 13.1 7.7
Month
Figure 4.5: NRW for BP39 and BP40 by Water Audit Method
Figure 4.5 shows the results of NRW for the two adjacent zones using Water audit
method. Taman Batu Pahat, BP39 shows a higher percentage of NRW compared to
Taman Makmur, BP40 from January until June. When inspecting the areas, BP39 have
smaller size of consumers compare to BP40 which is 609 and 1191 of connection each.
For this period of time, average flow for BP39 is quite high than six month later. This is
expected, as the boundary valve for the adjacent area BP40 was loose and some of the
water from BP39 is transferred to the adjacent zone. After doing some monitoring and
zero test pressure in July, the percentage of NRW is drops from 44.5 % in June to 6.8 %
in July. In August until December, the graph shows inconsistency in NRW percentages
due to unstable of monthly usage for the area due to events such as Hari Raya Aidilfitri,
school break and so on.
NRW percentage for BP40 is relatively lower than BP39. From January until June
the graph shows inconsistency in NRW but in July, SAJ reported that there was a pipe
burst occurs in BP40 and MNF value for this month is higher by 7.88 l/s compare to other
56
month but it is not giving higher value for NRW percentage in Water audit method. This
is because the pipe burst indicates leakage percentage and not reported totally as NRW in
water audit method. The higher NRW percentage at BP40 is in August with 29.1%. This
is expected, due to low customer consumption and higher water production for that
particular month.
After proving, mean NRW for BP39 is 15.96 % while for BP40 is 19.28%. These
results show after proving NRW level is decreased. Mean NRW percentages are only
considered after proving. This is because proving is just like meter calibration and set to
zero reading. The accurate results are obtained after done proving due to maintenance
works by water utilities for those particular areas.
CHAPTER V
CONCLUSIONS AND RECOMMENDATIONS
5.1
Conclusion
A comprehensive assessment on Non-revenue water (NRW) was conducted in
two areas, Taman Batu Pahat, BP39 and Taman Makmur BP40, in Batu Pahat in Johor.
This assessment has attempted to evaluate and update the local situation of NRW and
proposes appropriate solutions for the reduction and control of NRW. The assessment
included analyse of data from District Metering Area (DMA) using Step test and Water
audit method. Aims and objectives of this research are served as the guiding principles
toward achieving the results and conclusions. Conclusions drawn from this research are
as followings:
58
5.1.1
NRW components are identified
NRW components are classified into three main components which are real
losses, apparent losses and unbilled authorized consumptions. Volumes of real loss are
significantly higher than apparent loss. Average leakage percentages for BP39 after
proving is 5.61% while for BP 40 is 6.48%. NRW for BP40 is higher compared to BP39
due to the different in material of pipes installed and numbers of connections. BP40 have
installed Asbestos Cement (AC) pipe and BP39 have installed Ductile Iron (DI) pipe.
Since AC pipe is low in strength and durability, BP40 gives a higher percentages of
NRW due to those pipes. These pipes were easier to get cracked. DI pipe is high
mechanical strength and toughness compared to AC pipe.
After proving, average NRW percentage for BP39 was 14.43% while for BP40
was 19.75%. NRW percentage was done using Water Audit method. Water Audit method
considered all water production and water consumption in those particular areas. BP40 is
higher in NRW due to a higher number of connections and longer distance covered by
BP39.
5.1.2
Implementing District Meter Area method in determination of NRW
The two ways of assessing NRW explained in the previous chapter are Step test
and Water audit methods. Step test method uses MNF analysis to determine NRW
component which is real loss. However, MNF analysis uses field test data to quantify the
volume of real loss within the distribution network. The results can be compared directly
with the volume of NRW obtained from water audit method. As water audit method, step
test method required DMA in order to conduct MNF measurements. A DMA is a
hydraulically discrete part of the distribution network that is isolated from other
59
distribution system. It is normally supplied through a single metered line so that the total
inflow to the area is measured.
In residential areas such as BP39 and BP40, the MNF for these areas usually
occur between 2 am to 4 am. The MNF is the most meaningful piece of data as far as
leakage levels are concerned. The result obtained by subtracting the assessed night use
and exceptional night use from the minimum night time flow, known as the net night time
flow (NNF) and it consists predominantly of physical losses from the distribution
network. Water audit method is the difference between water provided and water
consumption.
Using both methods for identifying NRW will make sense because both methods
have their own advantages to reduce the amounts of NRW. By using Step test method,
leakage percentages can be identified. Continuous night flow measurements are very
helpful to identify leakages. Accordingly, the numbers of leakages can be identified
immediately. DMA measurements have clearly proven to be a good tool for identifying
and prioritizing areas for leak detection. Overall NRW was determined by the amount of
water provided and water consumption for each DMA using Water audit method.
5.2
Recommendations
Recommendations to achieve lower level of NRW are suggested as follows;
1. It was observed that average water pressure during step test of BP39 are much
higher than BP40, it is recommended that water pressure of the system be reduced
which may lead to the reduction of NRW. It is suggested to employ BP39
Pressure Reducing Valve, PRV to control the area, especially BP39.
60
2. A water utility embarking on the implementation of NRW strategy. SAJ needs to
monitor its progress. Boundary valves to neighboring water systems should be
inspected periodically to ensure they are in good and proper condition.
3. Water utilities should have mechanism in place to detect trends of unauthorized
consumption. As an example, billing data should be reviewed for suspicious
trends that might reflect unauthorized consumption. For instance, active accounts
registered unchanged meter readings (zero consumption) might be indication of
meter tampering or faulty meters.
4. Pipe materials and number of connections is worth considered in determining pipe
tightness.
61
References lists
[1]
Thornton J., (2008), Water Loss Control. United States of America: McGrawHill. Second Edition.
[2]
Malaysian Water Association (MWA)., (2008),Malaysia Water Industry Guide
2008: Water Supply Statistic and Performance Indicators. Kuala Lumpur 2008
[3]
Ir. Zainuddin Md. Ghazali., (2009), Twinning Regional Forum Daejeon
Korea.2009
[4]
Farley.M et al., (2008),The Manager’s Non-Revenue Water Handbook: A Guide
To Understanding Water Losses. Ranhill.
[5]
Steve Ditcham .,(2008) , “Asia Census Metering Systems.District Metering: A
Means of Addressing NRW”.
http://www.lwua.gov.ph/tech_mattrs_08/district_metering.htm
[6]
[7]
[8]
Lambert A., (2000), “Losess from Water Supply Systems: Standard Terminology
and Recommended Performance Measures”. International Water Association.
Morrison J., Tooms S., Regers D., (2007), DMA Management Guidance Notes,
International Water Association.
Lambert A., Fantozzi, M., (2005), “Recent advances in calculating Economic
Intervention Frequency for Active Leakage Control, implication for calculation of
Economic Leakage Levels” IWA International Conference on Water Economics,
Statistics and Finance, Rethymno.
62
APPENDIX A
63
APPENDIX B
Aged Meter (Faulty Meter)
New Customer Meter
64
Automatic Meter Reader
SAJ Water Utilities show me how they collect reading from each premise