Fact Sheet
WATER EFFICIENCY
Water Loss Control
Water Audits and Proactive Programs Bring
High‑Level Benefits
Quick Facts
• Water Losses are comprised of Real Losses (leaks) and Apparent Losses (theft
and meter under-registration).
• Water Loss Control Programs promote overall water efficiency by reducing
leaks and increasing revenue recovery.
• Small breaks may go unnoticed for a long time, causing more loss than a
main break.
• Leakage is a key indicator of distribution system performance.
Overview
Continuing droughts and increasing frequency of main
Estimating Water Losses
There are no federal regulations requiring utilities to
breaks have led utilities, regulatory agencies, and stake-
provide detailed reporting of water use, so finding
holders to focus on water efficiency and water loss
an accurate estimate of water losses (both Real and
control programs. Media attention is focused on leakage,
Apparent Losses) is difficult. The following estimates
yet leading water utilities are focusing on overall water
must include some assumptions. The U.S. Environmental
efficiency, which means reducing distribution of water
Protection Agency (EPA) and the American Water Works
where no revenue generation occurs, including Real
Association (AWWA) have estimated that “as much as
Losses (leaks) and Apparent Losses (water theft or meter
18% of water might be lost each year to leakage, meter-
under-registration). Many resources have been published
ing inaccuracies, data handling errors, and unauthorized
recently to meet this challenge.
consumption,” amounting to “approximately 5.9 billion
gallons per day” (CNT 2013). Another estimate is from
waterrf.org
Water Audits
The goal of water loss control programs
is not to reduce Real and Apparent
Losses to zero, but to determine
the appropriate actions to cost
effectively reduce leaks and increase
revenue recovery.
A water audit is a thorough examination of a water utility’s data, records, accounts, and procedures regarding
the volumes of water moved from input through the
distribution system to the customer. AWWA recommends
their water audit methodology as a best practice and it is
defined in M36 Water Audits and Loss Control Programs
(AWWA 2016b) . AWWA’s M36 and the Water Research
Foundation's (WRF) Real Loss Component Analysis
(Sturm et al. 2014) provide the guidance and tools to
build a water loss control program.
the American Society of Civil Engineers, which cites
First Level: Top-Down Water Audit
240,000 main breaks per year and gives the U.S. drink-
A top-down water audit is an initial desktop assessment
ing water infrastructure a D grading (ASCE 2016). With
of records and should be performed annually and can be
an estimated water infrastructure spending shortfall of
performed using the “AWWA Free Water Audit Software”
$17 billion per year (AWWA 2012), it is estimated there
(AWWA 2016a) (see Figure 1). An example of the infor-
is a rising backlog of unreported failures and increased
mation that can be determined is Philadelphia’s 2006
losses from leakage.
water audit. It revealed considerable Apparent Losses
More accurate estimates of break rates and water losses
22% had meter malfunctions and 46% were vandalized by
come from research. Based on a literature review, Sturm
tampering (AWWA 2009).
and, of 12,000 customer accounts with zero consumption,
et al. (2014) found that the average pipe failure frequency
is approximately 25 failures/100 miles/year. The most
Fewer than ten states currently require an annual water
robust water audit data set to date is from Georgia, and
loss report or audit using the AWWA methodology. A
the median value of Apparent Losses was 5.96 gallons per
top-down audit contains performance indicators for
service connection per day and the median value of Real
financial and operational efficiency. AWWA states that
Losses was 52 gallons per service connection per day or
the infrastructure leakage index (ILI) and real losses (gal/
1,730 gallons per mile of main per day (Sturm et al. 2015).
service connection or mile of mains/day/psi) are the most
appropriate for utility comparisons (AWWA 2016b). In an
analysis of 812 water audits from five regions, the median
Proactive Water Loss Control Programs
ILI was 2.48 and median real losses were 39.88 gallons per
Most North American utilities employ a reactive strategy—
service connection per day (Sturm et al. 2014). A utility
repairing failures in a timely manner. However, proactive
should compare its own audits from year to year, working
water loss control programs can bring high-level ben-
to improve the data validity score.
efits because they don’t just focus on leaks, but rather
on utility efficiency of distributing treated water to the
Second Level: Component Analysis of Losses
customer and generating revenue from that action. A
(Looking for Leaks)
comprehensive approach can include improving meter
After a top-down audit, a more in-depth analysis may be
and record accuracy, leak detection surveys, and repairing
performed on either Real or Apparent Losses. This sec-
and replacing infrastructure.
tion focuses on reducing Real Losses because a free tool
Anticipated benefits include limiting wasteful source
collected data on reported, unreported, and background
has been created for that purpose. It requires a year of
water withdrawals, optimizing revenue recovery, increas-
leakage (see Table 1). Real Losses are primarily comprised
ing reliability and efficiency, preventing contamination,
of leaks from mains and service connections.
and improving system integrity (AWWA 2016b). Halifax
Water’s loss control program reduced system leakage
WRF’s report, Real Loss Component Analysis, and its
by 9 million gallons per day, with an annual savings
accompanying software tool, the “Leak Repair Data
of Can$550,000 (Kunkel et al. 2006).
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Water Efficiency
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Water Loss Control
Water
Exported
Billed Water Exported
(corrected
for known
errors)
Volume
from
Own
Sources
(corrected
for known
errors)
Revenue
Water
Authorized
Consumption
System
Input
Volume
Billed Authorized
Consumption
Unbilled
Authorized
Consumption
Billed Metered Consumption
Billed Unmetered Consumption
Unbilled Metered Consumption
Unbilled Unmetered Consumption
Unauthorized Consumption
Apparent Losses
Water
Supplied
Systematic Data Handling Errors
Leakage on Transmission and
Distribution Mains*
Water Losses
Water
Imported
Customer Metering Inaccuracies
Real Losses
(corrected
for known
errors)
NonRevenue
Water
(NRW)
Leakage and Overflows at Utility’s
Storage Tanks*
Leakage on Service Connections
up to the point of Customer
Metering*
*Italicized component volumes of Real Losses are not addressed in the AWWA software.
Source: AWWA 2016b
Figure 1. Standard water balance and terminology for finished water systems
Table 1. Types of leakage
Type of Leakage
Definition
Tools/Solutions
Background
Not detectable using traditional acoustic
• Pressure stabilization
Leakage
equipment
• Pressure reduction
• Main replacement
• Reduce number of joints/fittings
Unreported Leaks
and Breaks
Often doesn’t surface; is detectable with
• Pressure stabilization
traditional acoustic equipment
• Pressure reduction
• Main replacement
• Reduce number of joints/fittings
• Proactive leak detection and repair
Reported Leaks
and Breaks
Usually surfaces and is reported to utilities
• Pressure stabilization
by the public
• Pressure reduction
• Main replacement
• Optimized repair time
Source: data from Filho 2004
Water Efficiency
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Water Loss Control
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Collection Guide,” help to categorize leaks and perform a
component analysis of real losses (Sturm et al. 2014).
———. 2012. Apparent and Real Losses. Denver, Colo.:
American Water Works Association. Accessed June 3,
2016. http://www.awwa.org/portals/0/files/resources/
Actions to Reduce Water Losses and Increase
water knowledge/water loss control/apparent-real-
Revenue Recovery
losses-awwa-updated.pdf.
Pressure management is one leak management tool.
———. 2016a. “AWWA Free Water Audit Software.”
Pressure-reducing valves can reduce breaks and losses.
Accessed June 3, 2016. http://www.awwa.org/
In Halifax’s district metered areas, pressure-reduc-
resources-tools/water-knowledge/water-
ing valves resulted in a 10–30% reduction of breaks
loss-control.aspx.
(Fanner et al. 2007).
———. 2016b. M36 Water Audits and Loss Control
Programs. 4th ed. Denver, Colo.: American Water
Leak identification is another important leak management tool. An acoustic survey is the traditional method
Works Association.
CNT (Center for Neighborhood Technology). 2013.
for finding a specific leak. More expensive methods may
The Case for Fixing the Leaks. Chicago: Center
be worthwhile, such as continuous acoustic monitoring, or
for Neighborhood Technology. http://www.
satellite image analysis that detects a spectral signature
cnt.org/sites/default/files/publications/CNT_
of potable water touching soil (Schumi 2016).
CaseforFixingtheLeaks.pdf.
Fanner, P., J. Thornton, R. Liemberger, and R. Sturm. 2007.
Conclusion
Since the 1990s, the United Kingdom’s Leakage Initiative,
International Water Association, the AWWA Water Loss
Control Committee, and WRF have furthered the concepts and practices of water loss control and water
audits. Conservation has typically focused on the utility
Evaluating Water Loss and Planning Loss Reduction
Strategies. Project #2811. Denver, Colo.: Awwa
Research Foundation.
Filho, J. T. 2004. “Leakage and break components and
reduction tools” in Abastecimento de Água by M. T.
Tsutiya. São Paulo: São Paulo University.
Kunkel, G., C. Yates, and D. Hughes. 2006. “Sustaining
customer, but strides in water efficiency can be achieved
water resources through water auditing and loss-
through utility water loss control programs. AWWA
control innovations.” Drinking Water Research,
advocates the use of the their water audit method and
performance indicators because they have shown success
16(6): 2–7.
Schumi, P. 2016. “Out of this World Leak Detection.”
internationally and have the promise to improve the state
Water Online Radio. Podcast audio. August 3. http://
of practice in North America (WLCC 2003). Using best
www.wateronline.com/doc/out-of-this-world-leak-
management practices and multiple levels of water audits,
utilities can employ proactive strategies to discover
detection-0001.
Sturm, R., K. Gasner, T. Wilson, and S. Preston. 2014. Real
and repair leaks, become more efficient, reduce water
Loss Component Analysis: A Tool for Economic Water
losses (both Apparent and Real Losses), and increase
Loss Control. Project #4372a. Denver, Colo.: Water
revenue recovery.
Research Foundation.
Sturm, R., K. Gasner, and L. Andrews. 2015. Water Audits
References
ASCE (American Society of Civil Engineers). 2016. “2013
Report Card for America’s Infrastructure.” Accessed
April 1, 2016. http://www.infrastructurereportcard.org/
grades/.
in the United States: A Review of Water Losses and
Data Validity. Project #4372b. Denver, Colo.: Water
Research Foundation.
WLCC (AWWA Water Loss Control Committee). 2003.
“Committee report: Applying worldwide BMPs in water
loss control.” Jour. AWWA, (95)8: 65–79.
AWWA (American Water Works Association). 2009.
M36 Water Audits and Loss Control Programs. 3rd ed.
Denver, Colo.: American Water Works Association.
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Water Efficiency
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Water Loss Control
Last updated April 2017