Water audit in distribution network by establishing district metered area dma a necessity in assessing real

1. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
INTERNATIONAL JOURNAL OF CIVIL ENGINEERING
17 – 19, July 2014, Mysore, Karnataka, India
AND TECHNOLOGY (IJCIET)
ISSN 0976 – 6308 (Print)
ISSN 0976 – 6316(Online)
Volume 5, Issue 9, September (2014), pp. 01-08
© IAEME: www.iaeme.com/Ijciet.asp
Journal Impact Factor (2014): 7.9290 (Calculated by GISI)
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1
IJCIET
©IAEME
WATER AUDIT IN DISTRIBUTION NETWORK BY ESTABLISHING
DISTRICT METERED AREA (DMA) - A NECESSITY IN ASSESSING REAL
LOSSES COMPONENT OF NON-REVENUE WATER (NRW)
K. S. Renukumar1, Dr. PushpaTuppad2
1Student-M.Tech, (AEE, BWSSB – sponsored by CPHEEO), Dept. of Environmental Engineering,
Sri Jayachamarajendra College of Engineering, Mysore. India, renukumarks@gmail.com
2Associate Professor, Dept. of Environmental Engineering, Sri Jayachamarajendra College of
Engineering, Mysore, India
ABSTRACT
Due to continual growth of population, the availability of potable water is declining. Water audit is
one of the strategic tools that provide a realistic, scientific framework that categorizes all water usage
in the system and pinpoints how efficiently the system is operating and where the losses are
occurring. In Distribution network, it is a tool to overcome shortage, leakage and losses of water. In
this case study, water audit has been conducted for the distribution network for a single District
Metered Area in south Bangalore. The audit comprises of calculating the system input, real losses
and infrastructure leakage index.
Key Words: District Meter Area, ILI, Non-revenue Water, Water Audit
1. INTRODUCTION
Audits are preferred to ascertain the validity and reliability of information; also to provide an
assessment of a system's internal control [1]. Water audit is the most effective tool for water
management. The aim of a Water audit is to provide a rational, scientific framework that categorizes
all water use in the system. It is a tool to overcome shortage, leakage and other losses of water.
Water audit and its analysis will solve not only many water related problems but also saves precious
resources and public money. The water audit display how quantity of water flows into and out of the
distribution system and to the customer [2].
A portion of the total water use is leakage, which is due to inaccurate metering, unauthorized
use, etc. A water audit determines where and how much the water ends up at different locations. All
water systems lose some amount of water for a variety of reasons, which is not always easy to
measure. Water loss costs money, paid by the authorities and customers [3]. Some water loss is

2. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
unavoidable, and for the utilities, it is not cost effective to try to eliminate the loss of every drop of
water from the system. However, majority of the losses that occurs in water systems can be better
managed by using a water audit. Through water audit physical losses due to pipe leakage and other
losses due to metering errors, un-authorized connections and any free water given etc can be
measured across the distribution system.
Following are the advantages of Water auditing [2]:
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1. It provide decision making tools to utility personnel regarding water usage in the system to
make decisions about investing resources such as time, labor and money.
2. It allows managers to identify and efficiently reduce water losses in the system.
3. By reducing water at the source, delaying or avoiding capital investments can be achieved.
4. It identifies the revenue earning and non-earning component of the utility. Thus, revenue can
be increased by ensuring all appropriate measures.
5. It helps in creating the awareness among water users, which will help in managing the wasted
water.
It is estimated that 50 percent of Indians, will reside in urban areas by the end of year 2025
and will face severe water problems [4]. The reasons of water scarcity in many cities are attributed to
limited source and under performance of distribution networks. The underperformance can be
attributed to lack of finance, inadequate data, inappropriate system design, overlapping
responsibilities, inadequate training of personnel, lack of performance evaluation and regular
monitoring, etc [5].
Initiatives like reducing of Non-revenue Water (NRW) and water auditing through metering
of the water connections will result in reducing the wastage of water and increase the revenue to the
concerned authorities. Therefore, an Integrated Water audit approach towards plugging leakages is
necessary to save considerable quantity of water, improve pressures in the distribution system and
increase revenues to make the systems self-sufficient [6].
NRW is the difference between the quantities of water supplied to a city’s network and the
metered quantity of water used by the customers along with authorized unbilled usage [7]. The most
commonly used indicator to measure NRW is the percentage of share of water produced. Leakage is
usually the main component in developed countries, while in developing countries apparent losses
and unbilled but authorized consumption such as water provided for religious institutions, parks,
public fountain, etc are more relevant. NRW is estimated at 35-40% in developing countries like
India and 4% in developed countries like Japan. The World average NRW is estimated at 36.6% [6].
Benefits of NRW reduction, in particular to leakage component includes Financial gains,
delay of costly capacity expansion, Increased knowledge about the distribution system, Reduced risk
of contamination, more stabilized water pressure etc [8].
2. BACKGROUND OF THE STUDY
Like other big cities, Bangalore is also facing problem of shortage of piped water. Bangalore
Water Supply and Sewerage Board (BWSSB) is the governmental agency responsible for providing
Water supply and sanitary system to Bangalore city. The city’s present drinking water supply is just
over 1300 MLD [9]. The present NRW level in Bangalore city is in the range of 45%, out of which
leakage alone ranges from 70 – 85% [10]. Assessing and thereby reducing Real losses will greatly
improve the revenue of Organization, apart from other intangible benefits [11].
With this purpose in mind, an Integrated Water audit was taken up in a small area coming
under Kathriguppe service station (Vidya Nagar DMA) for the identification and assessing of Real
losses and corresponding Infrastructure leakage index (ILI).

3. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
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3. METHODOLOGY
As it is not possible to supply water to entire network at the same time, the same is divided
into different zones and water is supplied to each zone at different point of time based on the
availability. Generally, the tail end users will get low amount of water with less pressure [8]. Further,
it is also difficult to locate the wastages, assess inflow and outflow of water in the zone as the
network is interconnected with a number of mains. To overcome this situation, the zone is divided
into a number of District Metered Areas (DMAs) depending on topography of the area. Once, the
DMAs are delineated, it is easy to establish the actual amount of water fed in to system, its
consumption and also leakages.
Further, the standard water balance for performing water audit in the DMA is the framework
for categorizing and quantifying all water uses. The balance denotes all components of water in the
system such as billed, unbilled, real losses, and apparent losses etc, which are equal to the amount of
water input by the sources.
With this background, the methodology for the Water audit at the study area has been carried
out through following components:
3.1 Detailed Assets Surveys
Based upon the preliminary network maps, a tentative DMA boundary was formed. A
detailed survey pertaining to Assets, Customers, and Topography, etc was carried out in the study
area using sophisticated equipment like pipe locator, valve locator and cable locator. The customer
survey is conducted to capture information regarding existing numbers, size of connections, number
of families residing, alternate source/sources of water, free water usage like public stand posts / taps,
public toilets, parks and also to locate illegal connections.
3.2 Updation of GIS maps
Preliminary network data collected from BWSSB were validated at ground on sample basis
and were updated in GIS (Arc Info version 10.1). The collected details like name of road, no of
houses, average water demand, length, diameter, type, age of pipeline, position of valves etc, are
updated on continual asis in separate layers in GIS with clear links provided to physical benchmarks.
3.3 Network simulation using computer software
Before performing Network Modeling, the study area was checked for discreteness by
performing Pressure Zero Test (PZT). Here, each boundary valve was closed and the pressure and
flow at some selected points both within as well as outside the DMA were recorded through the data
loggers [12]. By analysing the pressure pattern in and around the DMA, it was observed that the
pressure behaviour inside the DMA is distinct from the outside pressure.
The collected details of reservoirs, rising mains, feeder mains, distribution mains, elevation at
nodes, pipe materials, diameters, length, age of pipes, number and type of valves, pressures, flows,
consumer connections, etc were fed in to the computerised model (Water Gems V8i software is
used).
The model was calibrated and simulated with the actual conditions. The simulated values and
actual field values were compared and variances due to shut valves (when they should be open) or
cross connections (where none exist), or dead ends not shown on drawings etc. were corrected.
Critical pressure was ensured at critical points w.r.t current delivery of service so as to ensure that all
the customers receive adequate supply. There are 152 nodes in the study area with the pressure head
ranging from 18 to 43.70m of head.
The formulae used for determining the velocity and thereby pressure is Modified Hazen
Williams with standard notations is:

4. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
4
v = 143.534 x CR r0.6575s 0.5525 (1)
The network was designed for 24x7 supply with minimum size of pipe as 100mm of DI or
MS material with no PVC pipes and replacement of pipes for House Service Connections (HSCs)
with MDPE pipes. Further, Pressure Relief Valves (PRVs) for Pressure management along with
Network strengthening with additional or shifting of valves to improve efficiency were ensured.
With input of all these parameters, the model was run for the pressure at the junctions.
3.4 Design establishing the DMA
Use of flow to determine the leakage level within a defined area of the network is the key
principle of DMA management [13]. The criteria are:
• Size of DMA (number of connections—generally between 1,000 and 2000)
• Minimum number of valves must be closed to isolate the DMA
• Fewer number of flow meters to measure inflows and outflows to lower the establishment
costs
• Ground-level variations within the DMA as the flatter area results more stable pressures and
area with undulation will result in uneven pressure.
• Easily makeable topographic features which can serve as boundaries for the DMA
After the confirmation of DMA as hydraulically discrete, the DMA was formally formed with
two District Meters (DMs): SW2DM0101 and SW2DM0102 on 200 mm dia pipeline at DMA inlet
points, where tapping was being done.
3.5 Determination of water balance
The terms used in the water balance are as follows [2]:
System Input Volume - The volume of treated water input to the DMA from all known sources.
Authorized Consumption - The volume of metered and/or unmetered water taken by registered
customers.
Water Losses – It is the difference between System Input and Authorized Consumption.
Billed Authorized Consumption - These are the components of Authorized Consumption which are
billed and produce revenue (also known as Revenue Water).
Unbilled Authorized Consumption - These are the components of Authorized Consumption which
are legitimate but not billed.
Commercial/Apparent Losses – It includes all types of inaccuracies associated with customer
metering as well as data handling errors (meter reading and billing), plus unauthorized consumption
(theft or illegal use).
Physical/Real Losses – It is the leakage and other physical water losses from the pressurized system.
Billed Metered Consumption – It is the all metered consumption which is billed.
Billed Unmetered Consumption - All billed consumption which is calculated based on estimates or
norms but is not metered.
Unbilled Metered Consumption – This is the Metered Consumption which is for any reason
unbilled.
Unbilled Unmetered Consumption – This is the Authorized Consumption which is neither billed
nor metered.
Unauthorized Consumption – This consists of any unauthorized use of water through illegal
connections.

5. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
Customer Metering Inaccuracies and Data Handling Errors – This is caused by customer meter
inaccuracies and data handling errors in the meter reading and billing system.
Leakage in Distribution Mains - Water lost from leaks and breaks in distribution pipelines.
Leakage on Service Connections up to point of Customer Metering - Water lost from leaks and
breaks of service connections.
Revenue Water – These includes the components of Authorized Consumption which are billed and
produce revenue.
Non-Revenue Water (NRW) - The components of System Input which are not billed and do not
produce revenue.
Unaccounted-for Water (UFW) – This is equal to quantity of Physical and Commercial Losses.
This is NRW minus Unbilled Authorized Consumption.
5
The International Water Balance is as shown in Table 1. Determination of Water balance
involves recording of System input volume captured through Data Loggers installed at the DM
cabinets for a period of 30 days, which will then be compared to the sales recorded by the billing
system and other consumptions. Following five step processes was carried out for successful water
balance calculations [5]:
3.5.1 Source Evaluation
Here the System Input was categorized based on different sources such as piped supply, bore-well
supply, etc with outputs, accurately.
3.5.2 Calculation of Authorized Consumption
It involves calculating Billed Metered Consumption and Billed Unmetered Consumption, as
both of these categories are billed by the system through review of the records. The information from
the above two categories were added together to determine Revenue Water. Subtracting Revenue
Water from System Input equals NRW.
Table 1: The International Water Balance
System Input Volume
Authorized
Consumption
Billed Authorized
Consumption
Billed Metered
Consumption
Revenue
Water
Billed Unmetered
Consumption
Unbilled Authorized
Consumption
Unbilled Metered
Consumption
Non-Revenue Water
Unbilled Unmetered
Consumption
Water Losses
Commercial Losses
Unauthorized
Consumption
Metering Inaccuracies
and Data handling errors
Physical Losses
Leakage on
Transmission and/or
Distribution errors
Leakage and Overflows
at Utility’s Storage
Tanks
Leakage on Service
Connections up to point
of Customer Metering

6. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
3.5.3 Evaluation of Commercial/Apparent Losses
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It is the water that is delivered to an end user – including unauthorized use but is not properly
measured or recorded. Flow measurements on distribution lines and isolation of lines using valves
were used to measure this component.
3.5.4 Evaluation of Physical/Real Losses
Real Losses are the physical escape of water from the distribution system, and include
leakage and overflows prior to the point of end use. Leakages at the distribution system were the
only component of Real losses, which was established by subtracting commercial losses from Water
losses component.
3.5.5 Performance Measurement
The new and most advance real loss indicator is the ILI. The ILI is a measure of how well a
distribution network is managed (maintained, repaired and rehabilitated) for the control of real
losses, at the current operational pressure. It is the ratio of Current Annual volume of Real Losses
(CARL) to Unavoidable Annual Real Losses (UARL). ILI has no units [14].
UARL (liters/day) can be calculated as:
UARL = (18xLm + 0.8xNc + 25 x Lp) x P (2)
Where; Lm = Length of mains (km); Nc = Number of Service connections; Lp = Total length of
private pipe, curb-stop to customer meter (km); P = average pressure (m).
4. RESULTS
4.1 Assets details
There were 12004m pipeline out of which Cast Iron (CI): 1355m(200mm), Ductile Iron (DI):
80m (150mm); 35m (200mm); 1132m (100mm), Galvanized Iron (GI): 38m (50mm), and Polyvinyl
Chloride (PVC): 8486m (110mm); 878m(160mm). There were 45 Nos (including23 new valves)
valves with diameter varying from 100 to 200mm. The area of the DMA is 0.371 km2.
4.2 Customer details
The majority of the meters were found to be in good condition. There are 996 connections,
out of which 917 are Domestic, 7 are High rise building, 40 are Non-Domestic and 32 are Partial
Non-Domestic connections.
4.3 Water balance
The source is evaluated for quantity through Loggers installed in the DM cabinets for a
period of 30 days, which are 8.839 ML and 40.266 ML respectively, to totalling to 49.105 ML.
It was observed that only Meter Reading Errors were found to be dominant and remaining
components such as unauthorized consumption, Storage and Service connection losses, etc., which
were physically verified, were found to be negligible. Metering errors are established by selecting
5% of sample meters through bench testing. The percentage inaccuracy for the age wise connection
is derived by weighted average method, which was found to be -0.75% of the total inflow (-1.56% of
the billed consumption), which indicates that recording of consumption was less than the actual.
Hence, the Real loss of the system worked out to be 50.58%. The various water audit components are
balanced in Table 2 [15].

7. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
7
CARL (liters/day) = (24.839 x 106x12)/(365x996) = 819.9,
UARL (liters/day) = ((18x12.004) + (0.8x996) + (25x (996x3))) x 28.68 = 14.18
Then, ILI = CARL/UARL = 819.9/14.18 = 57.82.
Table 2: Water Balance of DMA
System Input Volume = 49.105 (100%)
Authorized
Consumption =
23.898 (48.67%)
Billed Authorized
Consumption =
23.898 (48.67%)
Billed Metered
Consumption = 23.898 (48.67%)
Revenue
Water=
23.898
(48.67%)
Billed Unmetered
Consumption = 0 (0%)
Unbilled
Authorized
Consumption = 0
(0%)
Unbilled Metered
Consumption = 0 (0%)
Non-Revenue Water = 25.207 (51.33%)
Unbilled Unmetered
Consumption = 0 (0%)
Water Losses = 25.207
(51.33%)
Commercial
Losses = 0.368
(0.75%)
Unauthorized
Consumption = 0 (0%)
Metering Inaccuracies and Data
handling errors 0.368 (0.75%)
Physical Losses =
24.839 (50.58%)
Leakage on Transmission and/or
Distribution errors 24.839 (50.58%)
Leakage and Overflows at Utility’s
Storage Tanks = 0 (0%)
Leakage on Service Connections up
to point of Customer Metering = 0
(0%)
5. CONCLUSION
ILI with values greater than 8 needs to be discouraged [1]. As the ILI is 57.82, it is high time
to take up the leakage reduction program on top priority.
6. ACKNOWLEDGEMENTS
The authors wish to thank The Chairman, BWSSB, Bangalore and Staff, as well as Mr. M.
M. Jaiswal, Project Manager, M/s Larsen Toubro limited, Bangalore and his team for the
Technical and equipment support towards development of this research work.
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17 – 19, July 2014, Mysore, Karnataka, India
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