I                     WATER AUDITS AND WATER  Loss CONTROL
   Environmental Protection
This document provides an introduction to water loss control and information on the use of water audits
in identifying and controlling water losses in public water systems. Water audits are the first step in a
three-step process for controlling water loss. A water audit is followed by intervention to identify losses
and implement solutions and then by an evaluation of intervention measures and the needs for further
improvement. This document is intended for small and medium-sized water systems, as well as state
programs and technical assistance providers that regulate or support these systems.
The Water Loss Problem

Public water systems face a number of challenges including aging infrastructure, increasing regulatory
requirements, water quantity and quality concerns and inadequate resources. These challenges may be
magnified by changes in population and local climate. It has been estimated that:

    •   The United States, will need to spend up to $200 billion dollars on water systems over the next
       20 years to upgrade transmission and distribution systems.1
    •   Of this amount, $97 billion (29 percent) is estimated to be needed for water loss control."
    •   Average water loss in systems is 16 percent - up to 75 percent of that is recoverable."

A water loss control program can help water systems meet these challenges. Although it requires an
investment in time and financial resources, management of water loss can be cost-effective if properly
implemented. The time to recover the costs of water loss control is typically measured in days, weeks,
and months  rather than years."  A water loss  control program will also  help protect public health
through reduction in potential entry points for disease-causing  pathogens.

Understanding Water Use and Water Loss

Much of the  drinking water infrastructure in the United States has been in service for decades and can
be a significant  source of water loss through  leaks.  In addition to leaks, water can  be  "lost" through
unauthorized consumption  (theft),  administrative  errors,  data  handling  errors, and  metering
inaccuracies  or  failure. The  International  Water Association  (IWA) and the American Water Works
Association (AWWA) have developed standard terminology  and methods  to assist  water systems in
tracking water losses and in performing water  audits. The standard terminology includes the terms
authorized consumption, real loss, apparent loss and non-revenue water that are used in this document.

    •   Authorized  Consumption is water that is used  by  known  customers of the water  system.
       Authorized consumption is the sum of billed authorized consumption and unbilled authorized
       consumption and is a known quantity.  It also includes water supplied to other water systems.

       Real Losses, also referred to as physical losses, are actual losses of water from the system and
       consist of leakage from transmission and distribution mains, leakage and overflows from the
       water system's  storage tanks  and  leakage from service connections up to and  including the
       Apparent losses, also referred to as commercial losses, occur when  water that should be
       included  as revenue generating water  appears as a loss due to unauthorized  actions or
       calculation  error.  Apparent losses consist of unauthorized consumption, customer metering
       inaccuracies, and systematic data handling errors in the meter reading and billing processes.
       Non-Revenue Water (NRW) is water that is not billed and no payment is received.  It can be
       either authorized, or result from apparent and real losses.  Unbilled Authorized Consumption is
       a component of NRW and consists of unbilled metered consumption and unbilled un-metered
What are the Benefits of a Water Loss Control Program?

A water loss control program helps to identify real or physical losses of water from the water system and
apparent losses, the water that is consumed but not accounted for.  Real losses represent costs to a
water system through the additional energy and chemical  usage required to treat the lost water.
Apparent losses represent a loss of revenue because the water is consumed but not accounted for and
thus not  billed. Once a water system identifies these real and  apparent losses through a water loss
control program,  it  can implement  controls to reduce them.  This can reduce the need for costly
upgrades and expansions due to population growth and increased demand. By reducing the amount of
water lost, the recovered water can be sold to consumers, generate revenue and meet water demands.
In some cases this can reduce the need to find additional sources. Water loss control programs are often
the most economical solution to increasing demand, especially in the short term.'
 What Does a Water Loss Control Program Look Like?
A  water loss control  program  consists  of
three major steps (see Figure 1). The critical
first  step is the water audit. A water audit
identifies and quantifies the water uses and
losses from a water system. The intervention
process addresses the findings of the water
audit through implementation of controls to
reduce  or  eliminate  water  losses.  The
evaluation step uses performance indicators
to determine  the success  of  the  chosen
intervention  actions.  Utilizing the standard
terminology and the three steps of a water
loss control program, systems can determine
their baseline water use and loss, prioritize
and implement water efficiency projects and
operational  changes,   and  evaluate  and
continuously  improve  their  water  loss
Figure 1. Components of a Water Loss Control
                Water Audit

Figure 2 provides a summary of the main data needs, action items and performance indicators for each
step of a water loss control program. The following sections will go into more detail for each step.
   Step 1 - Water Audit Data
   Step 2- Intervention
       Action Items
  • Gathering information.
  • Determining flows into and
   out of the distribution
   system  based on estimates
   or metering.
  • Calculating the
   performance indicators.
  •Assessing where water
   losses appear to be
   occurring based on available
   metering and estimates.
  •Analyzing data gaps.
  • Considering options and
   making economic and
   benefit comparisons of
   potential actions.
  • Selecting the appropriate
• Gathering further
 information, if necessary.
• Metering assessment,
 testing, or a metering
 replacement program.
• Detecting and locating
• Repairing or replacing pipe.
• Operation and maintenance
 programs and changes.
•Administrative processes or
 policy changes.
• No further action is
    Step 3 - Evaluation
  Performance Indicators

•Were the goals of the
 intervention met? If not,
 why not?
•Where does the system
 need more information?
• How often should the
 system repeat the audit,
 intervention and evaluation
• Is there another
 performance indicator the
 system should consider?
• How does the system
 compare to the last audit,
 intervention and evaluation
• How can the system
 improve performance?
Figure 2. Summary of Data Needs, Action Items, and Performance Indicators of a Water Loss Program

The Importance of Metering

Water meters, both at the source and the service connection, are very important for all aspects of the
water supply operations and make accurate water auditing possible. They make it possible to charge
customers based upon  the quantities of water that the customers consume. They record usage and
make billing fair for all customers. They can encourage conservation by making customers aware of their
usage as well as help detect leaks and establish accountability. Meter records provide historic demand
and customer use data that is used for planning purposes to determine future needs. Unmetered water
systems will need to consider some level of system metering to address water loss in the system.

A variety of meters exist and each type has its advantages and disadvantages. There is no single type of
meter that will accurately measure flow for all applications. To select the proper meter for a specific
application, a variety of factors should  be  considered in order for the meter to satisfy the location
requirements and conditions where it  will  be installed.  More  information about  the  types  and
applications  of  meters  can  be found in EPA's Control  and Mitigation of Drinking  Water Losses in
Distribution   Systems,  EPA   816-R-10-019,  November   2010.  The   document   is  available   at:
http://water.epa.gov/type/drink/pws/smallsvstems/technical help.cfm.

 Step 1 - How to Complete a Water Audit
A  water audit  is an  accounting of all  of the  water in  a water system  resulting  in  a  quantified
understanding of the integrity of the water system and its operation. It is the first step in formulating an
economically sound plan to address water losses. A preliminary water audit begins with the following
information and simple calculations :'

    1.   Determine the amount of water added to the system, typically for a one year period,
    2.   Determine authorized consumption (billed + unbilled), and
    3.   Calculate water losses (water losses = system input - authorized consumption)
           a.   Estimate apparent losses (unauthorized consumption  + customer meter inaccuracies +
               billing errors and adjustments)
           b.   Calculate real losses (real losses = water losses - apparent losses)

These steps are an example of a top down audit, which starts at the "top" with existing information and
records.  It  may also  be  known as a desktop audit or paper  audit since no  additional field work is
required. Water systems are dynamic.  The water audit process and calculation of the water balance,
when routinely  performed, is a useful guide for a system's water loss control program.  Water systems
can get started  using the data that is readily available, identify  any data gaps  and then work towards
improving their data.

After performing an initial top down audit it may become evident that some of the numbers are rough
estimates. The next action in the audit process  is to improve any initial estimates and begin reducing
non-revenue water losses.  A bottom up audit is often implemented after several top down audits have
been completed and can better quantify loss volumes that were  not revealed by the top down audit.  A
bottom up audit will help find apparent and real  losses and begins by looking at components or discrete
areas in the  utility's operations.  A bottom up audit assesses and verifies the accuracy of the water loss
data associated with individual components of the water system. A bottom up audit could include
estimates of water used in municipal operations such as fire fighting, distribution system flushing and
street cleaning, as well as metering of all authorized uses.1"

Bottom up audits are more costly since they are more labor and staff intensive.  The top down audit can
help to identify areas where  bottom up audit  efforts should be  concentrated. There are several
techniques and  methods used to perform a bottom up analysis.  They are described in  detail in Control
and Mitigation  of Drinking Water Losses in Distribution Systems, EPA 816-R-10-019, November 2010,
which can be found at: http://water.epa.gov/type/drink/pws/smallsvstems/technical  help.cfm.

Additional data often  needs  to be collected to  perform a  water audit. Additional data collection can
occur during the audit or intervention phase and  may include the following:'

    •   Locating leaks and losses can be accomplished through  an examination of billing records, flow
        monitoring,  visual   inspection   or  leak  detection   equipment  (e.g.,  acoustic,  thermal,
        electromagnetic, tracer). Through an examination of billing records, a water system may identify
        sudden changes in water usage at particular locations in the water system, which could indicate
       the need to  investigate further for possible leaks or theft. Flow monitoring can be conducted by
        examining individual customer meter  records, metered districts or through placement of
       temporary meters in suspect locations. These temporary meters clamp onto pipes and do not
        sacrifice the integrity of the pipelines.

    •   Condition assessment tools include traditional external visual inspections (e.g., periodic walk-
       over and opportunistic inspections of exposed  mains), internal visual inspection  technologies
       (e.g., closed circuit television (CCTV) camera inspections), pit depth measurements, destructive
       testing (e.g., test coupons) and non-destructive testing (e.g., ultrasonic testing).
    •   Hydraulic modeling can  be  used to  predict locations of leaks in a water system based  on
       physical and operating data of the water system. Calibration of these models to actual field data
       is essential to obtain realistic and usable results.

Water Audit Resources

       *~  AWWA provides Free Water Audit Software©, available at:
       *~  Georgia Department of Natural Resources, Georgia Water System Audits and Water Loss
           Control Manual, Version 1.0 (2011), available at:
           http://www.gaepd.org/Files PDF/GaWaterLossManual.pdf.
       *~  The Maryland Department of the Environment's Developing and Implementing a Water
           Conservation Plan, includes water audit worksheets and describes the development of a
           water conservation plan. The information is available at:
           state.md.us/assets/document/water  cons/WCP  Guidance2003.pdf.
       *~  The Texas Water Development Board's Water Loss Audit Manual (2008) includes a water
           audit worksheet. The manual and worksheets are available at:
       *~  The New Mexico Office of the State Engineer provides examples of water audits of public
           water systems using the IWA/AWWA process. Information is available at:
           http://www.ose.state.nm.us/wucp  accounting.html.
 Step 2 - The Intervention Phase
Interventions are actions taken by a water system to identify the specific sources of water loss  and
implement solutions. These actions can include:'

    •   Preventive measures such as design standards and effective maintenance
           o  Reliable construction and design standards allow a water system to maintain maximum
              structural  integrity  throughout its operating  life. Once  a water  system has been
              constructed  according to appropriate  design standards, effective maintenance can help
              to ensure the system  operates at optimal  performance throughout its  lifespan  and
              ensure that repairs are made proactively.
    •   Meter installation, testing and replacement
           o  Accurate metering is important for all  phases of a water audit. Meters record usage and
              monitor demand, encourage conservation,  help detect leaks and make it possible to
              charge customers for the water they use.

    •   Leakage management

           o  Detecting,  pinpointing  and repairing leaks generates event data that refines  and
              confirms the water losses identified in the water audit.
           o  Pressure management evaluates areas of excessive pressure and implements controls
              that reduce pressure to cut pressure-sensitive background leakage and reduce rupture
    •   Pipe repair and replacement
           o  Once a  leak has been  detected and  located,  the pipe can  be  repaired or replaced.
              Repairing and replacing pipes requires trained personnel, the right tools and  the proper
              inventory of parts and materials.
 Step 3 - The Evaluation Phase
The evaluation phase is important for ensuring an efficient and effective water loss control program.
Comparison of the water system to industry benchmarks or past audits can document improvements in
water loss control and allow a water system to track its progress. Use of performance indicators such as
those mentioned above can  help  to  ensure  meaningful interpretations of the evaluation and to
encourage continuous improvement. The evaluation will answer questions such as:

    •   Were the goals of the intervention met? If not, why not?
    •   Where do we need more information?
    •   How often should we repeat the Audit, Intervention and Evaluation process?
    •   Is there another performance indicator we should consider?
    •   How did we compare to the last Audit, Intervention and Evaluation process?
    •   How can we improve performance?

Benchmarking for Small Systems

Conducting a water audit allows a  system to monitor its water loss  performance over time and compare
itself to other systems. This process is  known as benchmarking and uses a  collection of performance
indicators to numerically evaluate different  aspects of the water system.  Performance indicators need
to be consistent, repeatable and presented in meaningful  standardized units.  Some  examples are
breaks per mile of distribution main per year, gallons of water lost per service connection, and gallons of
leakage per mile of distribution main per year. Because conditions at small systems can vary so greatly,
benchmarking can become a difficult practice as many performance indicators may not be consistent or
comparable across small systems. However, the  basic steps of top-down water audits,  metering and
water loss control efforts can help small systems conserve their resources and improve their long term

Performing a water audit and developing a complete water loss control program does not have to be
overwhelming. By beginning with the basic steps and  principles outlined in this document, any water
system can begin the process of identifying and mitigating water losses. Additional resources available
to assist water systems in performing water audits include the following:

    *~ EPA Office of Ground Water and Drinking Water, http://www.epa.gov/drink/
    *~ EPA Office of Water, Water Infrastructure: Moving Toward Sustainability.
    *~ Association of State Drinking Water Administrators, http://www.asdwa.org
    *~ The Alliance for Water Efficiency . http://www.allianceforwaterefficiency.org
    *~ American Water Works Association, http://www.awwa.org

Resources are also  available to  assist water  system customers in conducting a water audit of their
premises. These resources include the following:

    *~ The Maryland Department of the Environment provides instructions on how to conduct a home
       water audit as well as a spreadsheet that calculates current use using customer entries.
       ams/WaterPrograms/Water Conservation/Water  Auditing/index.aspx
    *~ Broward County Florida Water Services provides a worksheet for plumbing fixtures and
       appliances to calculate residential water use and provides average use for comparison.
    *~ The City of Corvallis, Oregon, Utilities Division provides information for residential customers on
       checking for leaks using the water meter, measuring or estimating flows in plumbing fixtures
       and measuring water used in landscaper irrigation.
1 U.S. Environmental Protection Agency. 2009. Drinking Water Infrastructure Needs Survey Fact Sheet, EPA 816-F-
09-003. http://water.epa.gov/infrastructure/drinkingwater/dwns/factsheet.cfm.
" Thornton, J., Sturm, R., Kunkel, G., Water Loss Control Manual (2nd Edition), McGraw-Hill, 2008.
'"Texas Water Development Board, Water Conservation Task Force, Water Conservation Best Management
Practices Guide, November 2004. http://savetexaswater.org/bmp/.
Office of Water (4606M)                      EPA 816-F-13-002                       July 2013