Non Revenue Water Reduction Strategy
Dated: September 2011
Report Name:
Non Revenue Water Reduction Strategy
Report Custodian:
Gary McLay, Asset Systems
Checked by:
Brian Jenkins, General Manager Assets
Approved by:
Executive Committee
Date:
5 September 2011
Version No:
5.0 Final
© Wannon Region Water Corporation
PO Box 1158
Warrnambool 3280
Dated: September 2011
Non Revenue Water Reduction Strategy
TABLE OF CONTENTS
1 Introduction and motivation ............................................................ 4 2 Background ....................................................................................... 6 2.1 2.2 2.3 2.4 2.5 Definition of Non Revenue Water .............................................................................. 6 Annual water balance ................................................................................................ 7 Indicators of water loss .............................................................................................. 8 Activities undertaken since the first Non Revenue Water Reduction Strategy .......... 9 Outcomes of the WSAA Project PPS-3 ..................................................................... 9 3 Wannon Water NRW performance ................................................ 11 4 Strategic approach to reducing water loss .................................. 15 5 Action Plan ...................................................................................... 20 6 Resource allocation........................................................................ 24 7 Conclusion ...................................................................................... 24 8 References ...................................................................................... 25 Appendix A: Calculation of the Infrastructure Leakage Index (ILI) . 27 Appendix B: Relative size of Water Distribution Zones – 2010/11 ... 29 Appendix C: Summary of NRW Statistics 2006/07 to 2010/11.......... 30 List of Figures:
Figure 1 2009-10 NRW levels for Water Utilities between 20,000 to 50,000 Connected
Properties ..................................................................................................................................... 5 Figure 2 NRW volumes for Wannon Water (2006-2011) ........................................................... 11 Figure 3 NRW Loss Rate Indicators for Wannon Water (2006-2011) ........................................ 12 Figure 4 %NRW & ILI Performance Indicators for Wannon Water (2006-2011) ........................ 12 Figure 5 NRW Loss Rate for Water Distribution Zones (2007-2011) ......................................... 13 Figure 6 Graphic illustration of gradual increase in leaking at East Warrnambool ..................... 14 Figure 7 Concept of the Economic leakage Level (ELL) ............................................................ 18 List of Tables:
Table 1: Breakdown for a water balance assessment (Lambert 2003) ........................................ 7 Table 2 Summary of ‘Lessons Learnt’ from WSAA Project PPS-3 ........................................... 10 Table 3: Projected water loss per system (MWH 2007) ............................................................ 11 Table 4: Action Plan to Implement the NRW Strategy ............................................................... 20 Table 5: ILI ranges ..................................................................................................................... 28 Page 3 of 30
Non Revenue Water Reduction Strategy
1 Introduction and motivation
With the increasing stress on available freshwater supplies, consumers cannot be expected to
“increase” the available water resource through a reduction in demand alone. Losses in the
system need to be addressed as part of supply management. This should be seen as one of the
main target areas for “creating” more available water. Water loss not only amounts to less
usable water, but also in potential increased charges due to additional treatment and distribution
costs. The extra costs due to lost water are passed on to consumers, who are required to pay
higher tariffs to offset these losses.
Under section 6.a of the Statement of Obligation (DSE 2007), Wannon Water is required to
“manage water resources in a sustainable manner”, and section 15.1.d instructs the Corporation
to implement programs for “reducing leakage and minimising other losses of water from its
works to an economically sustainable level”. Hence, the tabling of this water loss reduction
strategy document entitled “Non Revenue Water Reduction Strategy”.
In addition, in pursuance of the Wannon Water Vision and Mission, this strategy revision
continues to support the following relevant objectives defined in the Wannon Water
Sustainability Policy document (Wannon Water 2009):


More efficient use of resources to reduce operating costs; and
Setting targets to reduce:
 water consumption including that of customers across the South West; and
 energy consumption and greenhouse emissions.
There are a number of benefits, direct and indirect, from embarking on a program to minimise
water loss:
 Economic benefits through savings in pumping and treatment costs when delivering less
lost water;
 Appropriately sized infrastructure which does not have to accommodate downstream lost
volumes;
 Future infrastructure investment costs can be delayed to later years;
 The carbon footprint is reduced due to more efficient use of pumps and chemicals;
 Assists in meeting per capita water consumption reduction targets as identified in the
Water Supply Demand Strategy;
 Spare resource capacity is made available for residential and industrial growth;
 Additional water is made available for environmental flows;
 Less stress is placed on the natural environment, especially aquifers;
 A better understanding and knowledge of the water supply system is achieved by
undertaking an audit of the system and future monitoring of the data; and
 The image of the Corporation is improved, especially where customers are encouraged
to reduce their consumption.
In the first Non Revenue Water Reduction Strategy, it was reported that the average for water
losses in Australia was reported in 2003 as 9.6%, reportedly due mainly to Unavoidable Annual
Real Losses1 (UARL) and water meter inaccuracies (Girard & Stewart 2007). The Water Supply
Demand Strategy 2007-2055 assumes the leakage in Wannon Water’s reticulation networks
ranges from 8% to 15%2. The overall water loss was 13.3% and 15.5% in 2006/07 and 2007/08
respectively3. This provided the initial motivation to address Non Revenue Water (NRW) issues
1
The UARL are the inherent losses in water systems and is expressed as function of the length of mains and supply piping,
number of service connections and the average operating pressure.
2
Current field data suggests that this can be as much as 50%
3
The water loss was reported as 10.75% for 2006/07 in the Water Plan (Wannon Water 2007)
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Non Revenue Water Reduction Strategy
in Wannon Water. Since then the 2010 National Performance Report from the National Water
Commission has moved away from percentage NRW reporting to a more unbiased NRW
indicator – the Real Losses / Service Connection / Day. As shown in Figure 1, as one of the
smaller water utilities, Wannon Water has the second highest level of NRW. It is noted that
Darwin has a high level of water main breaks while Wannon Water is six times lower. The
ongoing high reported NRW levels in Wannon Water continue to provide motivation for lowering
NRW to more acceptable levels.
Figure 1 2009-10 NRW levels for Water Utilities between 20,000 to 50,000 Connected Properties4
A reduction in these losses could be achieved through a number of interventions such as
leakage detection and repair, pressure reduction, pipe replacement program, cathodic
protection of pipelines against corrosion, changes to the methods for mains flushing and
reservoir cleaning and installing peak balancing capacity. Wannon Water has set a self imposed
target of less than 12% loss by 2015. This strategy revises the earlier strategy to point the way
forward to achieving this target and, where economically viable, to reduce NRW losses.
4
National Water Commission, National Performance Report 2009-10 Urban Water Utilities, p. 55 Accessed from
https://www.wsaa.asn.au/Publications/Documents/2009-10%20Urban%20National%20Performance%20Report%20%20Comparative%20Analysis%20part%20a.pdf
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Non Revenue Water Reduction Strategy
2 Background
2.1 Definition of Non Revenue Water
In the last 20 years, NRW has been identified as a major issue for water utilities to manage.
While there is a very precise definition of NRW by the International Water Association that is
summarised below in 2.2 Annual Water Balance, there is still some confusion about terminology
by the Essential Services Commission (ESC). In the definition of terms for ESC Key
Performance Indicators (KPIs), the following definition is provided for Non Revenue Water:
“Non revenue water - Regional & Metropolitan
 Unaccounted water is the difference between the volume of bulk water supplied and
the volume of water billed to the water businesses customers.
Leakage - Regional & Metropolitan
 Current annual real losses divided by the unavoidable annual real losses.
 Indicator should be calculated in accordance with IWA methodology.”
Essential Services Commission, Metropolitan and Regional Businesses Performance
Indicators, 19/07/2004, p. 5-6, Accessed from:
http://www.esc.vic.gov.au/NR/rdonlyres/A764A12F-410B-4C04-B204D1057A0856FB/0/WaterPerfRepFrame_DecisionAttachmentA190704.pdf
It is clear from this definition that NRW does not include ‘process’ losses from water treatment
facilities, losses from transfer systems and evaporation and seepage from open earthen
storages. It applies to losses downstream of ‘System Inputs’ to water distribution systems that
provide water directly to consumers.
While Wannon Water needs to ensure that there are not unacceptable water losses in its
transfer systems, the reporting of NRW applies only to water distribution zones. This revised
strategy will also address reductions in transfer, storage and treatment process losses.
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Non Revenue Water Reduction Strategy
2.2
Annual water balance
The International Water Association through their Water Loss Task Force has provided clear
guidelines on the disaggregation and calculation of NRW and water losses parameters for water
distribution networks. These guidelines are now internationally recognised and were recently
endorsed as part of the recently completed WSAA Asset Management Project PPS-3 – Review
of Leakage Reporting and Management Practices.
There are a variety of aspects that contribute towards NRW as illustrated in Table 1 below.
Each of these is managed in a different way and will vary in size according to local
circumstances and operating parameters. To accurately quantify the size of each of these, they
need to be measured over the same time period, a challenge in particular for consumer
metering with various meter reading cycles. Accordingly, the water balance calculations are
usually done on an annual basis to reduce ‘lag’ errors.
Apart from System Input (Bulk) meter accuracy issues, it is also noted that a number of the
components of a water balance require estimates to be made since they are not directly
measured. In particular this includes estimates for unbilled unmetered consumption (e.g. fire
fighting, mains flushing, etc.) and unauthorised consumption (mostly illegal / water theft).
Despite meter accuracy testing of consumer meters, there is also uncertainty in consumer meter
inaccuracy estimates.
In overview, the calculation of non revenue water and water losses is not an exact science; it
requires the use of the best information available, diligence in the procurement and use of the
information and basing decisions on trends rather than apparent short term variations in the
data. There are also issues in the cost to obtain quality and accurate information and the
benefits in using this information to drive down NRW.
Table 1: Breakdown for a water balance assessment (Lambert 2003)
Billed Authorised
Consumption
Authorised
Consumption
Unbilled Authorised
Consumption
System
Input
Volume
(Bulk Water)
Billed metered consumption
Billed unmetered consumption
Unbilled metered consumption
Unbilled unmetered
consumption
Unauthorised consumption
Apparent Losses
Customer metering inaccuracies
Water Losses
Current Annual
Real Losses
(CARL)
Revenue
Water
Leakage on transmission and
distribution mains
Leakage and overflows at
storage tanks
Leakage on service
connections, to customer meter
NonRevenue
Water
(NRW)
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Non Revenue Water Reduction Strategy
2.3
Indicators of water loss
There are a variety of water loss indicators ranging from the very simple (but biased)
percentage NRW (%NRW) to the more comprehensive Infrastructure Leakage Index (ILI)
recommended by the International Water Association and recently endorsed by the WSAA PPS3 Project for Australian conditions. Within this spectrum, there are ‘compromise indicators
including unit losses to the number of consumers and unit losses compared to the length of
water mains. The reality is that there is no perfect NRW indicator, but some indicators are
better than others.
The challenge is that the quantum of NRW is affected by a number of factors including:

The number and type of consumers,

Unit consumption rates,

The length and size / materials of the water mains,

Static and operating pressures
While the %NRW is a simple indicator, it is highly influenced by the above factors. For a given
water system where these factors do not change, the %NRW is suitable to track changes in
water losses. For comparing different systems and/or changing system conditions, this indicator
is now internationally recognised as a poor and misleading indicator. More robust indicators
should be used such as has recently been adopted by the National Water Commission.
Other commonly used indicators are NRW rates compared to either the length of water mains
(where service connection density is low) or the NRW rate compared to the number of property
connections (where connection densities are high). These indicators are better than %NRW but
still do not consider the impact of water pressure which will significantly impact leakage rates.
The ILI is considered the most robust and unbiased NRW indicator. The method to calculate
this is shown in Appendix A. While it does include assumptions about acceptable water losses
and a linear relationship between pressure and leakage rates, the ILI indicator is an indicator
that permits comparison of NRW losses between different water distribution systems and
systems with changing characteristics. It should be noted that the ILI only assesses the losses
from the water distribution systems. It excludes ‘Apparent losses’ and ‘Unbilled Authorised
Consumption’ – these need to be assessed with separate NRW indicators. For Australian
conditions, these losses are generally small – most NRW is due to losses from leaking
pipework.
Cognisant that currently the ESC is still using the %NRW indicator for state wide performance
reporting, the section below on Wannon Water NRW performance has included %NRW.
Complementing this, indicators on unit NRW losses and the internationally recognised ILI have
been included.
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Non Revenue Water Reduction Strategy
Activities undertaken since the first Non Revenue Water Reduction
Strategy
2.4
The initial emphasis of the first Non Revenue Water Reduction Strategy has been to understand
the NRW issues confronting Wannon Water. During the last two years the following key
activities have been undertaken:

Setting up and holding regular three monthly meetings of the Non Revenue Water Group
that provided guidance and direction (including the creation of the first Non Revenue
Water Reduction Strategy) on NRW issues. This group included members from all
relevant sections in Wannon Water and was led by the General Manger Assets;

Meter installation program. This included programs to provide information on the NRW
performance of water supply zones (including segmented water distribution system
where appropriate) to identify unacceptable NRW levels and target remedial actions.
This work was undertaken as two programs:
o
Under the umbrella of the Water Supply Demand Strategy, the installation of 19
flows meters at a budgeted cost of $1.45 million at nominated locations in water
distribution zones;
o
Under a commonwealth Department of Environment, Water, Heritage and the
Arts (DEWHA) funded program, the installation of 17 flow meters at a budgeted
cost of $1.2 million) in the Otway systems to quantify harvested volumes and
transfer losses to the various water distribution zones. This project is currently a
work in progress’;

Investigation and introduction of procedures for calibration of bulk flow meters;

Introduction of the concept of Maximum Allowable Night Flow (MANF) based on UARL
(see Appendix A for definition) and the Weighted Average Ground Level (WAGL) to
determine the allowable night flow before active leak detection should be undertaken;

Following analyses of water balances for each water zone, undertaking targeted
analyses of Minimum Night Flow (MNF) measurements to determine water distribution
zones where leakage volumes are unacceptably high;

Targeted Active Leak Control (ALC) surveys using acoustic detection equipment either
by in-house staff or contracting out to specialists;

Review and assessment of unmetered consumption including fire fighting use,
unauthorised use of fire services, improved management of ‘water carters’, connection
of unmetered consumers, and consumer meter accuracy trials;

Improved reporting of NRW flow volumes and indicators including tracking for various
water distribution zones. This task is now the responsibility of Reporting and Projects
Section in Systems Operations Branch.
Now that a good understanding of the NRW issues has been developed, the thrust of the next
step in managing NRW is to take this information and further target actions to better manage
NRW, also to take a more ‘hard nosed’ approach to the economics of NRW management in
Wannon Water.
2.5
Outcomes of the WSAA Project PPS-3
As part of its drive to better understand NRW management issues, Wannon Water participated
as one of 24 participants in the WSAA Asset Management Project PPS-3 – Review of Leakage
Reporting and Management Practices. After three stages over three years, this project
concluded in April 2011. There were many valuable ‘lessons learnt’ from this project that are
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Non Revenue Water Reduction Strategy
summarised below. There was extensive documentation including software system produced
from this project – refer to ‘References’ list for list of reports from this project.
Table 2 Summary of ‘Lessons Learnt’ from WSAA Project PPS-3
•
ILI water loss measures Okay
•
Problem is the Water Balances
–
Accuracy of the system inputs
–
Estimates of unmetered consumptions
–
Calculation of metered consumptions – lagging effects
–
Calculation of average pressure
–
Use no. of connections or no. of properties
•
Need to look at confidence of data / estimates in Water Balances
•
Understanding UARL
–
Understanding water loss components (background, unreported, reported)
–
Impact of local situations
•
•
Minimum Night Flows
–
Consumption estimates guidelines
–
Selection of typical MNF
•
–
•
•
can go as low as ILI = 0.7
stable period and median flow
Quick ILI as a guide
Economics
–
Rate of rise calculation
–
Intervention levels for ALC
–
Budget requirements
Pressure management impacts
–
 leak volumes,  leak / burst rate,  asset lives
–
Cause and effect concepts
–
Prediction guidelines
–
Pressure spike analysis
–
Water quality impacts – dead ends
–
Costs of establishing & operating Pressure Management Zones (PMZs)
For further information on the outcomes of this valuable project, reference to the various reports
produced as listed in the References. There were also 4 software systems provided from this
project ranging from WSAA support ‘Water Balance’ software, ‘Pressure Management’ software,
‘Economics of ALC’ software and ‘Leakage and Pressure Management Evaluation & Targeting’
software.
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Non Revenue Water Reduction Strategy
3 Wannon Water NRW performance
The key performance indicator for water loss used for the Performance Targets in the Water
Plan (Wannon Water 2007a) is the water loss expressed as a percentage of the annual bulk
supply. The self imposed target is set at 12%. As shown in graphs below, Wannon Water has
consistently been unable to meet this target.5
In the current Water Supply Demand Strategy – Demand Analysis Projections (MWH 2007), the
projected expected water losses expressed as a percentage of the projected bulk supply for
each system for the next five year period are listed in the following table6. This strategy is
currently being revised and will be finalised by March 2012.
Table 3: Projected water loss per system (MWH 2007)
Year
Otway system Hamilton system
2008/09
2009/10
2014/15
11.3%
10.5%
9.5%
7.7%
7.1%
6.5%
All other systems
(including Portland & Port Fairy
9.1%
9%
7.6%
In subsequent years it was expected to maintain the savings obtained by 2015, through
continued monitoring, leakage detection and repair work. As indicated below and in Appendix
C, these expectations need to be reviewed, as water losses have not declined as anticipated.
As shown in Figure 2 below, until 2010/11, NRW volumes generally declined leading to reducing
NRW loss rates and ILI reductions and generally increasing %NRW figures (illustrating one of
the shortcomings of the simple %NRW indicator). In the last year (2010/11), while the billed
consumption continued to decline, the NRW volumes increased leading to an increase in all
NRW performance indicator figures – see Figures 3 and 4. There will be some accrual
corrections to these figures, but they are not expected to change much.
Figure 2 NRW volumes for Wannon Water (2006-2011)
Wannon Water NRW volumes
Input Volume (ML)
Billed Volume (ML)
16,000
16,000
Water Volume (ML)
Loss (ML)
14,000
14,000
12,000
12,000
10,000
10,000
8,000
8,000
6,000
6,000
4,000
4,000
2,000
2,000
0
0
2006-07
2007-08
2008-09
2009-10
2010-11 Draft
Year
5
6
The Non Revenue Water was reported as 10.75% for 2006/07 in the Water Plan (Wannon Water 2007)
The savings under the Water Supply Demand Strategy are based on projected NRW being reduced by 25% by 2015.
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Non Revenue Water Reduction Strategy
Figure 3 NRW Loss Rate Indicators for Wannon Water (2006-2011)
Wannon Water NRW loss rate indicators
Loss (L/connection/day)
6
Loss (kl/km/day)
150
5
120
4
90
3
60
2
30
1
0
kl/km/day
kl/connection/day
180
0
2006-07
2007-08
2008-09
2009-10
2010-11 Draft
Year
Figure 4 %NRW & ILI Performance Indicators for Wannon Water (2006-2011)
Wannon Water NRW Indicators
% NRW
20%
2.50
18%
2.25
16%
2.00
Percentage NRW
14%
12%
1.75
NRW performance target set in the Water Plan & ESC KPI reporting
1.50
10%
1.25
8%
1.00
6%
0.75
4%
0.50
2%
0.25
0%
Infrastructure leakage Index (ILI)
ILI
0.00
2006-07
2007-08
2008-09
2009-10
2010-11 Draft
Year
As shown in Figure 5, while the NRW performance has not improved as expected, there have
been improvements in a number of water supply zones with several zones apparently worse.
Improved metering has been partly responsible for this as bulk meter inaccuracies have
improved leading to some improved figures and others worse. As indicated above, minimum
night flow monitoring has been used along with Active Leakage Control activities to locate and
reduce distribution losses.
As is apparent from Figure 5, the recent decline in NRW overall performance is due to the
Warrnambool zone. There has been substantial work done to segment this large zone and
several large leaks have been found. There is currently a concern about the bulk meter
accuracy that is being addressed and further zone segmentation is underway to continue to
identify localised areas of unacceptable water losses.
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National Performance Report
TOTAL
Warrnambool
Timboon
Terang
Tarrington
Simpson
Sandford
800
40%
700
35%
600
30%
500
25%
400
20%
300
15%
200
10%
100
5%
0
0%
Percentage of Total Connections
2010-11 Draft
Purnim
Portland
Port Fairy
Port Campbell
Peterborough
Penshurst
2009-10
Noorat & Glenormiston
Mortlake
Merino
Macarthur
Lismore & Derrinallum
2008-09
Koroit
Heywood
Hamilton
Glenthompson
Dunkeld
2007-08
Dartmoor
Coleraine
Cobden Urban
Cobden Rural
Cavendish
Casterton
Caramut
Camperdown Rural
Camperdown
Balmoral
Allansford
NRW Rate (Lit/Connection/Day)
Non Revenue Water Reduction Strategy
Figure 5 NRW Loss Rate for Water Distribution Zones (2007-2011)
Non Revenue Water (Lit/Connection/Day)
% of Total Connections
Non Revenue Water Reduction Strategy
As indicated above, part of the calculations for NRW include estimates for non ‘Real’ water
losses – Unbilled Authorised Consumption and Apparent Losses. While it is important to
manage the Unbilled Authorised Consumption (fire fighting, mains flushing, tanker water, etc.),
these are usually relatively small compared to other NRW volumes. Actions to manage these
issues have been introduced during the first NRW strategy period.
The larger proportion of non ‘Real’ water loss is usually customer meter inaccuracies. To
quantify the extent of these losses, also to validate meter replacement criteria, a random sample
of 687 20mm consumer meters were removed and bench tested for a range of flows from low to
high. These were tested over a range of flow rates as prescribed in the metering standard.
While the accuracy tests showed some trends of under registration as meters age and more
importantly with increasing flow volume, all the relationship explored are statistically
insignificant. It was concluded that apart from meters that had stopped working, there is little
support from the test results for a proactive meter replacement program. The average accuracy
of the meters tested was 0.9% under registration. This reduces to 0.45% under registration
when the stopped meters are removed from the sample group. The assumption in the NRW
calculations referred to earlier was 0.6% for consumer meter inaccuracies and 0.2% for other
non ‘Real’ water losses. The conclusion is that estimates are close to tests undertaken and that
non ‘Real’ water losses are relatively small compared to ‘Real’ water losses.
While it is disappointing that overall, and specifically in Warrnambool, that NRW has not
decreased in recent years, it is observed that NRW management programs often take several
years to take effect. In the early years as metering systems are improved, it is not uncommon
for NRW levels to increase followed by decreases to more acceptable levels as improved NRW
management systems and practices bed in and continuing attention to water loss control is
embedded in the organisation. Wannon Water has had its successes with increased
understanding of water loss volumes, the targeting of investigation and as illustrated in Figure 6,
the reduction of leak volumes once leaks are identified. Water loss control is an ongoing task
and as Wannon Water continues to target NRW management issues proactively, the water loss
volumes will decrease.
Figure 6 Graphic illustration of gradual increase in leaking at East Warrnambool
30
25
Flow (l/s)
20
15
5
0
Repaired leak
10
in
eas
In c r
aka
g le
at e
ge r
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Non Revenue Water Reduction Strategy
4 Strategic approach to reducing water loss
This document is the second Non Revenue Water Reduction Strategy. Arising from the first
strategy, a list of ‘Actions’ was produced following the approach proposed in the initial strategy.
The outline of this first strategy that was embedded in the ensuing NRW ‘Action List’ and the
tracking of these is as follows:

Improved internal co-ordination - Establish a NRW Working Group

Improved metering

Leak reduction
o
Bulk water balance analysis
o
Active leakage control
o
Leak detection and repair
o
Pressure management

Unmetered customers

Reduced storage losses – evaporation and seepage

Reduced treatment and water quality losses

Improved infrastructure management
The review in March 2011 of the Action List from the first strategy concluded that all actions
were either completed or were ongoing. The May 2011 meeting of the Non-Revenue Water
Group proposed that it was timely that the Non Revenue Water Reduction Strategy be revised
to take in account the current situation, the lessons learnt over the last few years and outcomes
of the WSAA NRW project PPS-3. The following revised strategy is proposed to move Wannon
Water towards the next step as it seeks to further improve NRW management of its water
distribution systems.
As indicated above, the thrust of the first strategy and the ensuing activities was to better
understand NRW management issues in Wannon Water. There has been a substantial
improvement in flow monitoring, both water balances and night flow assessments. Overall, the
results have revealed that the situation is actually worse than that initially assessed as a result
of inaccuracies in flow monitoring. It is noted that the accuracy of some meters still need to be
verified, and also that the DEWHA funded program for improved metering of the Otway’s
system is still underway.
The strategy proposed below seeks to put Wannon Water in a strong position to argue the case
that it is managing NRW responsibly and effectively based on ‘State of the Art’ knowledge and
techniques in the industry, being cognisant of local situations (e.g. Limestone geology in
Warrnambool), and economic analyses to make value based decision on NRW management in
Wannon Water. An 11 part approach is proposed:
1. Non Leakage NRW issues
The assessment to date indicates that these aspects of NRW are relatively small in Wannon
Water overall. Given recent outcomes from the WSAA PPS-3 project, it is proposed that
these early assessments need to be reviewed using ‘State of the Art’ water balance
methodology to identify which (if any) sources of non-leakage NRW should be targeted for
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Non Revenue Water Reduction Strategy
further detailed investigations and development of ‘sub-strategies for management of these.
Aspects of non-leakage NRW issues to be investigated will include:








Water quality - flushing / air scouring of water mains
Fire fighting water use
Water tanker use
Consumer meter under-registration at low flows
Unmetered customers
Unmetered fire services
Water tankering
Water theft
Pending the development of appropriate non-leakage sub-strategies, these will be
implemented to achieve containment and/or reduction in non-leakage NRW. It is noted that
this must be cost justified to give a balance of implementation costs against the value of
reduced non-leakage NRW and/or the value of improved revenue as is appropriate.
2. Bulk meter (‘System Input’) accuracy verification
As highlighted by Stage 1 of the WSAA PPS-3 project, the single biggest issue with NRW
management is the accuracy of the ‘System Input’ flow meters. Errors in these meters can
have a significant impact on assessed NRW levels for water distribution systems. This has
already been highlighted above for Warrnambool that has apparent increasing NRW levels.
A procedure for ‘Confirming Bulk Meter Accuracy’ has been prepared and now needs to be
implemented on a periodic basis to ensure that bulk meters do provide reliable
measurement of system input volumes and flow rates.
3. Further segmentation of water distribution zones and DMA zones
There has been improvement in zone metering which is not complete yet. As proposed by
NRW management specialists and implemented in other water utilities and pending the
results of initial zone NRW assessments, further segmentation of water distribution zones
into ‘District Metering Areas’ (DMAs) may be required to track down and periodically assess
zones that have unacceptably high leakage levels.
Pending verification of bulk meter accuracies, Warrnambool is a strong candidate for further
segmentation and detailed assessment.
As practiced in other water utilities, depending on the economics and local situations, DMAs
may be permanent sites or temporary sites assessed using insertion probes or bypass
metering.
4.
‘System Input’ metering program – for water zones and permanent DMAs
This element of the Non Revenue Water Reduction Strategy includes completion of the
current metering program and installation of additional bulk flow meters to complete ‘system
input’ metering for effective monitoring (water balance and night flow monitoring) of NRW
levels.
These ‘gaps’ will be addressed through agreed additional ‘system input’ metering and
improved data collection and processing to reliably and timely collect and process measured
flow volumes and rates.
Page 16 of 30
Non Revenue Water Reduction Strategy
Complementing the installation of additional metering and information processing systems,
improved documentation of flow metering is required including how ‘system inputs’ for NRW
are measured and what data is used to calculated Water Balances for each water
distribution zone and DMA.
5. Reporting of NRW from Water Balances
Currently a variety of reporting forms and methods have been used to report on NRW water
levels. This is true within Wannon Water and also within the Water Industry. The WSAA
PPS-3 project identified this as a key issue to be able to reliably compare different water
utilities and different water distribution systems. It is understood that WSAA is currently
lobbying for a uniform approach to NRW water balance assessment and reporting.
Within Wannon Water it is proposed that the standard WSAA Water Balance template and
calculation method be used.
Further it is proposed that an agreed format and program for reporting (including map
based, tables and graphs) be adopted within Wannon Water. This will include periodic
reporting and identification of problem / suspect issues.
A key principle for reporting in Wannon Water is that any suspected problem should be
validated by other NRW assessment techniques to avoid both under reporting and over
reporting NRW levels to key stakeholders.
6. Minimum Night Flows (MNF)
A key method for validating suspected high NRW levels from water balances and breaks
and bursts evaluation assessments of reported and unreported leaks is the assessment of
night flows. This is not without its challenges as demonstrated in the WSAA PPS-3 project.
Referring to this project, a number of techniques and guidelines for the effective use of
minimum night flow analysis have been recommended. It is proposed that Wannon Water
should adopt these recommendations as part of its MNF analyses.
Further it is proposed that a cyclical program be set up for review and trending of MNFs
based on SCADA and logger information. This includes setting up data capture and
analysis systems for MNF assessments, the comparison of MNF results with water balances
to define / confirm problem / suspect issues and the periodic reporting and identification of
problem / suspect issues.
7. Management Reporting
As part of NRW reporting, to periodically report adopted Wannon Water NRW performance
indicators including comparative analyses to key stakeholders so that the overall picture of
the NRW situation is kept current. The reality is that NRW levels for Wannon Water are
currently higher than targets adopted by the ESC, and that we currently have one of the
highest NRW levels in Victoria and amongst our peer water utilities in Australia. It is
important that we keep the NRW issue high on the agenda so that Wannon Water can
demonstrate that it is actively addressing the situation.
In addition to performance indicator reporting of statistics for the whole of Wannon Water, it
should also provide comparative information on:



Temporal trends
Geographic patterns
Comparison with peers
Page 17 of 30
Non Revenue Water Reduction Strategy
While the NRW strategy is expected to be reviewed in 2014 as part of a three year cycle,
performance indicator reporting should be regularly reviewed to identify if a review /
adjustment of strategic directions for NRW management is required before this.
8. Leak Detection and Repair
Leak detection activities should be based on the results of NRW flow volume monitoring to
identify areas / zones for detailed investigation. This investigation may require further
segmentation of the zone into temporary DMAs to define a smaller area with unacceptable
loses.
Once an area of concern has been identified, leak detection on water mains and property
services using appropriate leak detection equipment and techniques should be undertaken
to determine location of ‘unreported leaks’.
Following identification of ‘leak marks’, pipework rectification / repair will be done as soon as
reasonably practicable. This includes reporting of work done in relevant ‘Work Order’
systems.
The guiding principle with leak detection is the timely detection of leaks and repair. It is
noted that it is usually the duration of the leak that impacts more on the volume of lost water
than any other parameter.
9. Economic Leakage Levels (ELL)
The above aspects of the Non Revenue Water Reduction Strategy put into place the
elements to quantify and locate sources of NRW in Wannon Water. Complementing this is
the need to quantify what leakage levels are economic to chase and to repair and those
levels that are non economic. As illustrated in Figure 7, the Economic Leakage Level (ELL)
is more than the UARL and less than the CARL and can be managed by a variety of ways.
The challenge is to estimate for a given system, it characteristics and environment, what is
the appropriate ELL.
Figure 7 Concept of the Economic leakage Level (ELL)
Page 18 of 30
Non Revenue Water Reduction Strategy
It is proposed that Wannon Water will seek to indentify Economic Leakage Levels for its
water distribution systems. Appropriate ELL techniques for Wannon Water situations will be
determined after consideration of the recommendations from WSAA PPS-3 project. These
will be applied to identify key targets for examination of ELL in Wannon Water followed by
analyses / investigations to quantify ELL for the selected target areas.
These ELL assessments will form the basis for targeted and justified water loss reduction
activities in Wannon Water.
10. Revise NRW targets for Wannon Water
As stated earlier, the current self-imposed target set in 2005 was a %NRW level of 12%.
Since then, there have been many lessons learnt about NRW management in Wannon
Water. It is considered prudent that this NRW target needs to be reassessed both in terms
of an appropriate indicator and a target that is realistic. This revision of NRW targets needs
to be based on reliable and confident estimates of NRW and appropriate ELLs for Wannon
Water. Criteria for selection of NRW targets should include:


Robust and useful NRW KPIs for Wannon Water
Target criteria for these KPIs for the range of scenarios encountered in Wannon
Water water-supply pipe networks
Having built a strong case for revision of NRW targets, the NRW strategy further proposes
that these need to be discussed and negotiated with relevant stakeholders for agreement
and adoption of these targets by relevant parties such as Wannon Water’s regulators.
11. Pressure / surge management
The WSAA PPS-3 project focussed on pressure management as an effective and proactive
approach to reduction of NRW water loss volumes, also to improve leaks and burst
performance and extend the life of water mains. The initial assessment to date has
indicated that there is limited scope in Wannon Water for pressure management. One of the
lessons learn from the WSAA PPS-3 project was that even a small reduction in operating
pressures and targeted pressure management in low areas of water distribution zones can
deliver benefits to the water utility.
It is proposed that Wannon Water should consider the recommendations / outcomes from
the WSAA PPS-3 project for pressure management applicability in Wannon Water. Further
potential candidates for surge management / pressure control should be identified and
appropriate business cases prepared to provide the justification for selective pressure
management in Wannon Water. Pending approval of these business cases, they will be
implemented as appropriate.
Page 19 of 30
Non Revenue Water Reduction Strategy
5 Action Plan
To implement the above strategy, the following Action Plan is proposed. It is anticipated that
most of the investigations and changes in NRW management will be complete by mid 2012
allowing any significant investment in NRW management to be identified and included in the
next Water Plan. Post mid 2012, many of the NRW management actions become ‘Business as
Usual’. They are included in the Action Plan below to illustrate the sequence of actions leading
to improved NRW management in Wannon Water.
Table 4: Action Plan to Implement the NRW Strategy
Actions
Item
1.
a.
Responsibility Date Due
Non Leakage NRW issues:
Overview investigation of Apparent Losses issues – to determine Asset Planning Dec 2011
those issues that need further investigations. Target aspects
include:








Water quality - flushing / air scouring
Fire fighting water use
Water tanker use
Consumer meter under-registration
Unmetered customers
Tanker Water
Water theft
Unmetered Fire Services
b.
Tanker metering – to improve knowledge of the volume of water
extracted from water zones by water tankers. Implement the
‘EasyFill’ project in partnership with savewater for metering of
tankers
Retail Services
Oct 11
c.
Consumer meter accuracy investigations – continue
investigation of consumer meter accuracy by sampling of meters
and accuracy testing for a variety of flow rates
Retail Services
Ongoing
d.
Fire fighting use – investigations and as appropriate metering to
understand the quantity of water used by fire stations
Asset Planning
Mar 2012
e.
Develop a program for identification and metering of unknown
fire services
Retail Services
Dec 2011
f.
Air scouring – develop and apply methodology to measure the
water used
System
Operations
Mar 2012
2.
Bulk meter (‘System Input’) accuracy verification:
Develop a Meter Accuracy Verification Program that includes all
meters – Bulk entitlement, Transfer and Distribution flow meters
System
Operations
Dec 2011
a.
Page 20 of 30
Non Revenue Water Reduction Strategy
Item
Actions
b.
Responsibility Date Due
Procurement, maintenance and verification of portable flow
monitoring equipment used for checking bulk meter accuracy,
also for short term flow metering of DMAs, etc.
c. Implementation of the program for meter verification in
accordance with the Procedure for Verification of Bulk Meter
Accuracy
System
Operations
Ongoing
System
Operations
Ongoing
d.
Report on this program to the Non Revenue Water Group on a
six monthly basis
System
Operations
Ongoing
e.
Investigate the impact of flow meter accuracy issues on Water
Balance results – sensitivity analysis of variations in meter
accuracy
System
Operations
Mar 2012
3.
Segmentation of water distribution zones:
Completion of mapping / schematics to define zoning and
accompanying metering - Timboon and Casterton
System
Operations
& GIS
Oct 2011
System
Operations
Dec 2011
a.
b.
Develop a Boundary Zone valve inspection and maintenance
program
c.
Review the results of the Warrnambool segmentation program
Asset Planning
Dec 2011
d.
Identify segmentation of zones to better monitor NRW levels
(Water Balances and Minimum Night Flows) to identify suspect
areas and targets for Active Leakage Control
Asset Planning
Jun 2012
System
Operations
Jun 2012
4.
‘System Input’ metering program:
a. Define additional zoning, metering and valving requirements for
improved NRW monitoring in water zones and permanent DMAs
b.
Installation of additional ‘hardware’ (flow meters, valving, etc.) to
monitor sub-zones and DMAs
System
Operations
Water
Plan 3
c.
Data collection of ‘system input’ meters – additional SCADA /
loggers to link into NRW information systems
System
Operations
Water
Plan 3
5.
Reporting of NRW from Water Balances:
Asset Systems / Dec 2011
Review of WSAA PPS-3 ‘Leakage Reporting and Management
Practices’ project outcomes for improved and standardised NRW Asset Planning
and
reporting in Wannon Water
a.
b.
Standardising of NRW reporting templates and procedures in
Wannon Water
System
Operations
Asset Systems
& System
Feb 2012
Page 21 of 30
Non Revenue Water Reduction Strategy
Item
Actions
Responsibility Date Due
Operations
c.
Comparison of NRW reporting with other Victorian water
corporations to ensure consistent and comparative reporting of
NRW levels
GMA & GMSD
Dec 2011
IWA TSSIG
System
Operations
Ongoing
6.
Minimum Night Flows (MNF):
a.
Review of WSAA PPS-3 ‘Leakage Reporting and Management
Practices’ project outcomes for undertaking analysis and
reporting of Minimum Night Flow assessments
b.
Implementation of agreed MNF analysis techniques and monitor
night flows on a monthly basis to identify unacceptable NRW
performance and candidates for Active Leakage Control
activities
System
Operations
Ongoing
c.
Monitor trends in SCADA to identify trends in MNF on an annual
basis
System
Operations
Ongoing
7.
Management Reporting:
Development of summary NRW performance indicator reports
for reporting the overall NRW position to key management
stakeholders
System
Operations
Oct 2011
a.
b.
Analysis of NRW performance indicator trends and patterns
including:
 Temporal trends
 Geographic patterns
 Comparison with peers
c.
Preparation of NRW management reports as follows:
 Quarterly report to the Non Revenue Working Group
a.
b.
Asset
Ongoing
Systems/System
Operations
System
Operations
Ongoing
 Quarterly report to Executive Committee
GMA
Ongoing
 Six monthly progress report to Board
GMA
Ongoing
Asset Planning /
System
Operations
Ongoing
System
Operations
Nov 2011
System
Operations
Ongoing
 Annual report to be included in the WSDS Demand Side
Working Group’s Annual Report
8.
Asset Systems / Nov 2011
Asset Planning
& System
Operations
Leak Detection and Repair:
Complete current list of Leak Detection activities
Investigate the application of alternative leak detection
technologies to improve the identification of leak marks
Page 22 of 30
Non Revenue Water Reduction Strategy
Item
Actions
c.
Develop and adjust as new information becomes available a
prioritised program of leak detection and repair based on the
analysis of night flows and water balances
d. Implement the leak detection program to identify locations of
suspect leaks for further investigation by appropriate means
such as dig-ups
9.
a.
Economic Leakage Levels (ELL):
Based on recommendations from authorities in economic
leakage levels analysis (e.g. the results from the WSAA PPS-3
project), evaluate the Economic Leakage Level for all water
supply systems in Wannon Water
b.
Discuss the results of the ELL study and prepare
recommendations for adoption of ELLs for Wannon Water
10.
NRW targets for Wannon Water:
Revision of target leakage levels following the determination of
ELLs
a.
Responsibility Date Due
System
Operations
Ongoing
System
Operations
Ongoing
Asset Systems / Sep 2012
Asset Planning
NRW Working
Group
Dec 2012
Executive
Mar 2013
GMR
Mar 2012
b.
Approach the ESC to change the method of reporting NRW to
more unbiased NRW indicators
11.
Pressure / surge management:
Asset Systems / Oct 2011
Review of WSAA PPS-3 ‘Leakage Reporting and Management
Practices’ project outcomes for pressure/surge management and Asset Planning
their applicability / relevance to Wannon Water
a.
b.
Identify areas for pressure/surge management
c.
Improve monitoring of pressures in reticulation zones to quantify
pressure patterns including static, dynamic and transient
pressures in water supply zones
d.
Prepare a Business Case for pressure/surge management
infrastructure for inclusion in Water Plan 3
Asset Planning
Dec 2011
System
Operations
Ongoing
Asset Planning
Mar 2012
Page 23 of 30
Non Revenue Water Reduction Strategy
6 Resource allocation
In the last few years there has been significant NRW management improvement actions
undertaken funded from the normal operational budgets of the relevant departments, from funds
arising from the Water Supply Demand Strategy and more recently a grant from DEWHA for
bulk meter installation in the Otways systems. Metering issues have largely been addressed
although there are still some remaining.
The current strategy focuses on improving and targeting NRW management in Wannon Water
based on improved information, lessons learnt in recent years and the results of studies and
research within the water industry such as the WSAA PPS-3 project.
At the last NRW Group meeting, it was decided that all monitoring and reporting functions for
NRW management would be managed by the Manager Reporting and Projects Section of the
Systems Operations Branch and strategic directions and analysis to be managed by the Assets
Planning Branch. The Retail Services Branch will continue to be responsible for customer
related aspects, including customer metering. The NRW Working Group will continue to monitor
and overview NRW management activities in Wannon Water.
The cost of these activities will continue to be funded out of normal operational budgets of the
relevant departments. Additional activities such as further flow meter installations, setting up of
DMAs and other special NRW projects will continue to be funded from allocations from the
Water Supply Demand Strategy. Provision for special NRW management expenditure is being
made in the next Water Plan to complement the Business as Usual budgets for the day to day
management of NRW.
7 Conclusion
The strategy builds on the initial strategy to provide a more focussed approach to managing
NRW in Wannon Water. The approach will ensure the quality and reliability of NRW information
and move towards a strong assessment of the economics of NRW management to build a
sound business case for the revision of NRW targets and any improvement actions required.
The NRW Working group will continue to provide the overviewing and coordination of NRW
management in Wannon Water with responsibilities for NRW monitoring undertaken by Systems
Operations and the longer term planning undertaken by Asset Planning.
It is anticipated that following the recent extensive work undertaken to improve NRW monitoring,
that NRW levels will gradually start to fall. The current cause for concern is the apparent large
increases in Warrnambool that significantly affect the overall results for Wannon Water. There
is significant potential for reducing NRW levels but this will take some time to realise. In the
longer term, Wannon Water will aim to achieve economic levels of NRW management such that
it does not burden its customers with additional costs to reduce NRW below economic levels.
Page 24 of 30
Non Revenue Water Reduction Strategy
8 References
DSE 2007. Water Industry Act 1994: Statement of Obligation Wannon Water, Department of
Sustainability and Environment, July 2007.
Girard, M & Stewart, R 2007. Implementation of pressure and leakage management strategies
on the Gold Coast, Australia: Case Study. Journal of Water Resources Panning and
Management 133 (3): 210-217. May/June 2007.
Lambert, A 2003. Assessing non-revenue water and its components: a practical approach.
Water21: 50-51. August 2003.
Lambert, A, Brown, T, Takizawa, M & Weimer, D 1999. A review of performance indicators for
real losses from water supply systems. AQUA 48 (8).
Lambert, A & McKenzie, R 2004. Best practice performance indicators: a practical approach.
Water21: 43-45. August 2004.
Liemberger, R, Brothers, K, Lambert, A, McKenzie, R, Rizzo, A & Waldron, T 2006. Water loss
performance indicators. Water Loss 2007 Specialist Conference, Bucharest, Romania,
23-26 September 2007.
Liemberger R, 2006. Introduction to Water Loss Analysis and Reduction, World Bank Institute,
Beijing
MWH, 2007. Wannon Water Demand Management Strategy: 50 year demand forecast,
Wannon Water, November 2007
Wannon Water, 2007a. Wannon Region Water Authority – Water Supply Demand Strategy –
2007:2055, Wannon Water, 30 March 2007
Wannon Water, 2007b. Final Submission Water Plan 2008/09-2012/13, Wannon Water, 8
October 2007
Wannon Water, 2009. Sustainability Strategy, Wannon Water, April 2009.
Wannon Water, 2009. Non-Revenue Water Reduction Strategy, Asset Planning Branch, July
2009
Wannon Water, 2009. Non-Revenue Water Strategic Actions, Wannon Water Non-Revenue
Water Group, August 2009
Wannon Water, 2009-11. Non-Revenue Water Group: Agenda and Minutes of Meetings no. 1
(Nov. 2009) to no. 10 (May 2011), Wannon Water
Wannon Water, 2010. Non-Revenue Water Programme - Flow Meter Capital Expenditure
(2010/11 - 2012/13) Proposal, Asset Planning Branch, April 2010
Wannon Water, 2011. Non-Revenue Water Group: Completed Action List, Asset Planning
Branch, March 2011
WSAA Asset Management Project PPS-3 – Review of Leakage Reporting and Management
Practices, 2009 – 2011, Reports produced for each stage:
Stage 1:
 Final report – Sources of Error and Uncertainty in Water Balance and
Performance Indicator Calculations (May 2009)
Stage 2:
 Guidelines relating to the Operations and Calibration of Bulk Flow Meters in
Water distribution systems (March 2010)
 Volume 1
 Volume 2A
 Volume 2B
 Guidelines for Assessment and Calculation of Average Pressure (WAGL)
(November 2009)
 Guidelines for Meter Lag Adjustments (November 2009)
Page 25 of 30
Non Revenue Water Reduction Strategy

Stage 3:








Review of Pressure Management Practices in the Australian Water Industry
(July 2010)
Report on Framework for Targeting Leakage and Pressure Management (30
March 2011)
Guidelines on Targeting Leakage using Night flow Measurements (30 March
2011)
Guidelines on Economic Intervention Principles for Active Leakage Control
(20 March 2011)
Guidelines on Information requirements for Pressure Management Zones
before and after Implementation (20 March 2011)
Guidelines on Predicting the Benefits of Pressure Management (21 March
2011)
Guidelines on Selecting, Operating and Evaluating Pilot Pressure
Management Zones (20 March 2011)
Guidelines on Valuing the Benefits of Pressure Management (21 March
2011)
Guidelines on Cost of Establishing and Operating Pressure Management
Zones (20 March 2011)
Page 26 of 30
Non Revenue Water Reduction Strategy
Appendix A: Calculation of the Infrastructure Leakage Index
(ILI)
The ILI is a NRW indicator that compares the estimated volume of losses from a water
distribution system (what is called ‘Real Losses’) to an estimate of the minimum achievable
losses (what is called ‘Unavoidable Real Losses’) from a well managed and maintained water
distribution system. This is shown diagrammatically as follows:
Infrastructure
Leakage
Index ILI
= CARL/UARL
Speed
Active
and
Leakage
Quality
of
Control
Repairs
Pressure
Pressure
Management
Management
UARL (litres/day)
= (18 x Lm + 0.8 x Ns) x P
Unavoidable
Annual Real
Losses
UARL
Speed
and
Active
quality
Leakage
of repairs
Control
Pipeline and
PipeAssets
Materials
Management:
Management:
selection,
Selection,
installation,
Installation,
maintenance,
Maintenance,
renewal,
Renewal,
replacement
Replacement
Current Annual Real Losses
CARL
Water losses in the water supply system are due mainly to high static pressures, burst pipes,
leaking valves and reservoirs and water treatment processes. Lambert et al (Lambert et al.
1999) show that leakage is a function of inline pressure, length of pipe lines and the number of
consumer connections, and not of per capita consumption. Extensive study of physical losses
from water supply systems has led to the conclusion that a certain amount of leakage is
unavoidable and as indicated above, has been termed the Unavoidable Annual Real Losses
(UARL), and can be calculated as follows (Lambert et al. 1999):
UARL = (18 * Lm + 25 * Lc + 0.8 * Nc) * P
Where:
Lm
= Length of bulk and reticulation piping (km)
Lc
= Length of piping from road to meter if not at road verge (km)
Nc
= Number of customer connections
P
= average pressure in the reticulation system (m)
The UARL equation has been used in countries such as Australia, Canada, UK, USA, New
Zealand, South Africa and Chile to mention a few (Lambert & McKenzie 2004). It has proven to
Page 27 of 30
Non Revenue Water Reduction Strategy
be robust in diverse international situations (Lambert 2003) where the system meets the
following criteria:



Nc > 50007
Nc / Lm > 20/km
P > 25 m
The recently completed WSAA Asset Management Project PPS-3 – ‘Review of Leakage
Reporting and Management Practices’ has thoroughly reviewed this methodology and its
applicability to Australian conditions. As shown in the above diagram, given that Australian
water utilities manage property services all the way to consumer water meters rather than just
the property boundary, it is proposed that the formula for UARL be adjusted for Australia.
The calculation of the total Real Losses is based on standard Water Balance calculations and
estimates. As shown in Table 1 above, it is the net of the ‘system inputs’ minus billed
consumptions and estimates for unmetered consumption that occur for various reasons such as
meter inaccuracy, legitimate but unmeasured use and illegitimate use such as water theft.
As noted above, because of issues associated with these estimates and the realities that
metered consumption is accrued consumption, calculations for Real losses are usually based
over long periods, hence the concept of Annual Real losses. Unless there are major changes in
consumption due to limited water resources, changing climate and/or changing consumptive
uses, calculation of Real Losses over a long period such as a year, is considered to generally
account for accrual issues with metered consumption.
The ratio obtained from the ILI equation gives an indication of the potential to minimise the
losses. Based on a wide range of case studies, an ILI of between 1 and 2 is deemed as
acceptable since it becomes uneconomical to spend time and money on reducing leaks and
apparent losses as illustrated in Table 5. Although a water utility may wish to still reduce losses
if water resources are a limiting factor for future growth. An ILI greater than 2 would indicate a
potential for loss reduction.
Table 5: ILI ranges
Range
1-2
2-4
4-8
>8
7
Response
Further loss reduction may be uneconomic unless there are resource shortages
Possibilities for further improvement
Poor leakage management, tolerable only if resources are plentiful and cheap
Very inefficient use of resources, indicative of poor maintenance and system condition in general
There have been moves to accept this formula for systems below 5000 connections. The ILI becomes less reliable when you
head into systems with under about 3000 connections. (Gary McLay)
Page 28 of 30
Page 29 of 30
Warrnambool
Timboon
Terang
Tarrington
Simpson
Sandford
Purnim
Properties
Portland
Port Fairy
Port Campbell
Peterborough
Penshurst
Noorat & Glenormiston
Mortlake
Merino
Macarthur
NRW Volume
Lismore & Derrinallum
Koroit
Heywood
Hamilton
Glenthompson
Dunkeld
Dartmoor
Coleraine
Cobden Urban
Cobden Rural
Cavendish
Casterton
Caramut
Camperdown Rural
Camperdown
Balmoral
Allansford
Percentage of Total
Non-Revenue Water Reduction Strategy
Appendix B: Relative size of Water Distribution Zones – 2010/11
Pipe length
50%
45%
40%
35%
30%
25%
20%
15%
10%
5%
0%
Non-Revenue Water Reduction Strategy
Appendix C: Summary of NRW Statistics 2006/07 to 2010/11
Water Distribution
Zone
Allansford
Balmoral
Camperdown
Camperdown Rural
Caramut
Casterton
Cavendish
Cobden Rural
Cobden Urban
Coleraine
Dartmoor
Dunkeld
Glenthompson
Hamilton
Heywood
Koroit
Lismore & Derrinallum
Macarthur
Merino
Mortlake
Noorat & Glenormiston
Penshurst
Peterborough
Port Campbell
Port Fairy
Portland
Purnim
Sandford
Simpson
Tarrington
Terang
Timboon
Warrnambool
TOTAL
2006/07
2007/08
2008/09
2009/10
2010/11 (Draft)
NRW NRW% L/Conn/Day Kl/km/Day ILI NRW NRW% L/Conn/Day Kl/km/Day ILI NRW NRW% L/Conn/Day Kl/km/Day ILI NRW NRW% L/Conn/Day Kl/km/Day ILI NRW NRW% L/Conn/Day Kl/km/Day
-3.3 -3.3%
-0.4
23.4 20.5%
2.9
22.0 17.6%
3.0
11.4
9.7%
1.5
14.7 12.7%
2.0
15.1 27.4%
1.8
5.2 11.8%
0.6
16.3 32.0%
1.9
5.5 12.6%
0.6
6.2 19.0%
0.7
59.5 14.4%
1.7 0.9
61.2 15.8%
98
1.3
47.5 12.3%
74
0.9
51.6 14.2%
80
1.0
52.2 15.3%
80
109.7 13.3%
2.5
115.1 15.7%
2.7
83.0 11.7%
1.9
108.5 15.6%
2.5
94.7 15.3%
2.2
9.8 28.1%
1.1
7.5 25.1%
0.9
5.4 21.5%
0.6
2.9 14.6%
0.3
5.0 31.7%
0.6
95.8 26.9%
3.8
65.7 20.8%
2.6
78.2 26.6%
3.1
82.6 30.7%
3.3
73.8 35.4%
2.9
1.3
9.1%
0.3
1.7 12.4%
0.4
7.3 42.8%
1.7
13.8 57.8%
3.1
0.7
5.8%
0.1
24.0
14.9
15.6
7.0 14.3%
3.2
52.6 61.9%
32.6 54.3%
34.2 61.0%
202
46.4
5.7%
146
-3.4 -0.5%
-11
20.4
3.1%
64
25.2
4.0%
78
65.0 10.9%
44.3 29.9%
3.8
27.6 21.4%
2.3
29.4 24.5%
2.6
53.8 34.7%
4.7
24.4 25.1%
2.1
15.5 55.4%
6.6
8.8 33.7%
3.8
3.6 16.3%
1.1
3.4 18.5%
1.0
5.2 28.7%
1.5
4.0
6.6%
0.2
5.5
9.1%
0.3
13.5 21.4%
0.7
12.5 19.9%
0.7
4.0
7.7%
0.2
-5.7 -13.3%
-0.5
-2.6 -9.8%
-0.2
32.9 74.9%
3.0
11.2 53.6%
1.0
15.8 38.2%
1.4
115.9
9.3%
62
0.6
135.2 11.3%
71
0.8
155.7 13.8%
83
1.0
174.6 16.2%
91
1.1
204.6 19.8%
105
22.8 11.7%
86
42.3 20.9%
156
22.4 12.9%
82
23.6 14.7%
87
25.8 17.9%
94
71.3 18.2%
303
64.8 21.7%
269
62.6 26.9%
254
44.0 19.9%
175
46.8 24.2%
185
21.0 13.1%
120
10.7
7.9%
61
18.5 12.3%
106
22.9 18.7%
130
18.3 18.2%
104
1.8
6.3%
29
2.6
9.6%
40
2.1
8.4%
33
2.5 11.2%
39
3.6 22.3%
56
4.5
8.7%
0.5
10.3 21.4%
1.2
6.8 16.5%
0.8
9.8 26.0%
1.2
4.9 14.9%
0.6
4.3
38.5 22.3%
2.9
30.8 21.8%
2.3
46.0 26.7%
3.5
56.9 35.8%
38.6 29.0%
2.9
9.9
6.3%
1.5
0.8
0.6%
0.1
7.4
4.9%
1.1
19.7 13.6%
2.8
6.1
5.2%
0.9
66.5 44.9%
584
77.3 51.8%
678
75.3 52.3%
666
32.5 35.0%
286
15.5 24.9%
136
3.0
6.6%
0.5
1.5
4.3%
0.2
-3.6 -10.8%
-0.6
1.0
1.5%
0.2
1.5
3.8%
13
0.3
6.5
9.8%
65
6.1
9.8%
59
0.8
1.4%
8
8.8 11.8%
83
6.5 10.2%
61
237.2 28.2%
322
7.4
147.3 19.5%
196
4.3
142.9 19.0%
188
4.2
73.1 10.6%
93
1.9
80.5 12.4%
102
360.0 16.3%
188
2.8
474.0 21.8%
243
3.9
394.0 18.6%
199
3.2
281.3 15.7%
139
2.2
302.3 18.0%
148
6.2 23.9%
2.0
5.8 25.2%
1.8
7.2 32.8%
2.3
6.6 33.3%
2.1
5.8 33.7%
1.8
5.9 16.9%
0.7
4.1 14.7%
0.5
5.9 19.5%
0.7
3.3 10.8%
0.4
4.2 22.3%
0.5
16.7 10.7%
3.5
6.3
4.9%
1.3
5.0
4.4%
1.0
10.2 10.7%
2.1
15.8 16.2%
3.3
8.8 23.2%
2.3
4.8 15.4%
1.2
7.9 21.2%
2.0
6.2 17.9%
1.5
12.7 34.0%
3.2
31.0 11.4%
80
1.2
51.7 19.5%
133
2.2
47.3 17.5%
120
2.0
30.5 12.8%
77
1.2
36.2 16.9%
91
201
37.3 16.9%
180
42.9 19.5%
204
32.5 16.4%
152
29.0 15.7%
135
41.7 16.0%
717.7 15.5%
143
3.3
753.7 17.0%
148
3.5
649.2 15.2%
125
2.9
808.9 19.3%
153
3.7 1,062.5 24.8%
197
2,186.2 15.5%
158
4.0 2.1 2,235.3 17.0%
159
4.3 2.2 2,088.3 16.4%
147
4.0 2.1 2,065.3 17.3%
143
4.0 2.1 2,282.7 20.3%
156
4.4
Note:
Blue highlighted figures are for %NRW above the average for Wannon Water
For NRW rates, loss / connection used when connection density > 20 connections / km water main and vice versa for loss rate / km
ILI calculated where no. of connections > 100 properties
Red Figures are for NRW rates and ILIs greater than the average for Wannon Water
Page 30 of 30
ILI
1.1
1.3
2.1
2.4
1.5
5.0
2.3