Tackling Water Loss - Why Conduct a Water Audit?

CJS - Tackling Water Loss.pdf

Focusing on Supply-Side Losses: Beginning with a Water Audit

By Carla J. Schumacher, P.E.
Note: This is #2 in a series of articles on water loss.

As discussed in the News from FOX Engineering Fall 2011 article “Tackling Water Loss: Why it Could Improve Your Bottom Line”, using the terms “unaccounted-for” and “unaccounted-for percentage” when referring to water loss can be misleading and is no longer recommended by the American Water Works Association (AWWA) Water Loss Control Committee, International Water Association (IWA) and others in the industry who are focusing their attention on supply-side losses.  

The IWA and AWWA have jointly developed a Water Audit Method for use by the international water community.  A foundation of this method is the IWA/AWWA Standard Water Balance that is based on the premise that all water supplied by a water utility can be accounted for by meters or estimation, and falls into the category of either consumption or loss.  IWA and the AWWA Water Loss Control Committee recommend replacement of the term “unaccounted-for” water with the term Non-Revenue Water (NRW).  The standard water balance is shown above in Figure 1.  This water balance is the basis for utilities measuring or estimating the amount of water produced, imported, exported, used and lost.  

Why Conduct a Water Audit?
While many utilities have ongoing leak detection efforts, meter replacement programs, and pipe replacement programs in different stages of implementation, very few have actually examined their system in such a way that is comparable to other water utilities across the country and throughout the world regarding water loss within the community water system.  Prior to the development of the Standard Water Balance by IWA/AWWA, definitions for water consumption and water loss have lacked standardization, making it difficult to compare one utility to another and to identify where the problems exist within the water system.  The value of the IWA/AWWA water audit method lies in the consistent terms used for consumption and water loss, as well as providing a set of rational performance indicators to enable comparison of specific utility characteristics.

In an AWWA Water Loss Control Committee presentation “Taking Control of Your Water Losses: System Water Audits” presentation by George Kunkel, P.E., Philadelphia Water Department on November 7, 2008, Mr. Kunkel made the argument for promoting water supply efficiency as a standard business practice.  

Water supply efficiency would be evidenced by 1) low water leakage losses, 2) minimal unbilled water consumption, 3) minimal unauthorized consumption, and 4) auditable operations.  

He also noted three historical shortcomings within the U.S. Drinking Water Supply including: 1) Technical - not all water supplied by a water utility reaches the customer, 2) Financial – not all of the water that reaches the customer is properly measured or paid for, and 3) Terminology – historically, a lack of standardized definitions of water and revenue losses.

Accountability to the public is an issue that every public entity must deal with, particularly when asking to raise water rates.  
•    What problems lie within your water system that if dealt with could improve your financial bottom line?  

•    Do you have meters that are under-reading and therefore under-charging your consumers/customers?  
•    Do you have slow water leaks on service lines that have gone undetected or unrepaired?  
•    How do you decide and justify where you should spend your limited resources within your water system to get the most return on investment?  

This is where a water audit can help.

The Water Audit
Accountability starts with a water audit that follows standard methodology and a consistent process of data gathering, analyzing, and reporting on an annual basis.  This is essentially a paper exercise where you begin with information you already have on hand.  

AWWA’s Water Loss Control Committee has created Free Water Audit Software© (Version 4.2, 2010) that is available on the AWWA website at:

www.awwa.org/Resources/WaterLossControl.cfm?ItemNumber=47846&navItemNumb...  

This free software guides you through the process of conducting an initial audit that can then be redone each year to capture the results of efforts you have completed throughout the year and to mark progress.  As noted within the purpose section on the first page of the software “This spreadsheet-based water audit tool is designed to help quantify and track water losses associated with water distribution systems and identify areas for improved efficiency and cost recovery.  It provides a ‘top-down’ summary water audit format, and is not meant to take the place of a full-scale, comprehensive water audit format.”  Two example audits are included with the software.  

More comprehensive water audit methodologis  are presented and discussed in AWWA’s M36 Manual of Water Supply Practices Water Audits and Leak Detection third edition that was released in May 2009, and the Water Loss Control Manual, Second Edition (2008) sponsored by AWWA.  

A reporting worksheet is developed from data input into the audit software.  This worksheet summarizes the water supplied, consumed and lost within the system and attaches an associated cost.

System data such as length of mains, number of service connections, connection density, average length of customer service line, and average operating pressure are summarized.  Cost data is summarized and includes total annual cost of operating the water system, customer retail unit cost and variable production cost.  

Performance indicators related to financial and operational efficiency indicators are presented which include percentages and costs for non-revenue water and the annual cost of apparent and real losses.  Along with a data validity score, three priority areas for attention are identified that can be used by the utility to focus attention for the next year’s budget and manpower resources.

The AWWA’s WaterWiser web site provides additional resources and articles.  A recent addition to this website is an analysis report by the committee, Validated Water Audit Data for Reliable Benchmarking (2011) and 2011 Validated Water Audit Data that includes water loss findings from 21 North American utilities.

Carla Schumacher is a water/wastewater engineer with FOX Engineering and is compiling information on Iowa water utilities pertaining to audits and water loss.  If you are willing to participate in a survey, please contact Carla at cjs@foxeng.com or 515-233-0000.