Distribution System Water Audit (Water Loss)

System audits include quantifying all produced and sold water, and may include testing meters,verifying records and maps, and field checking distribution controls and operating procedures (AWWA 1999).

The objective of system audits is to determine the amount of water that is lost and unaccounted for in the system. System audits may identify losses from:

  • Accounting procedure errors
  • Illegal connections and theft
  • Malfunction distribution-system controls
  • Reservoir seepage, leakage, and overflow
  • Evaporation
  • Detected and undetected leaks

    Available Water Savings Estimates

    No study considering the persistence of savings from leak detection has been found.

    The assumptions regarding how much earlier leaks are detected with a program than without a program are not well supported.

    Confidence in Estimates
    Low. To obtain reliable estimates of water conservation from leak repair, one needs to measure leakage rates and how they may change over time.

    Program and Device/Activity Cost Estimates

    Program Costs
    Supplier program costs may include:

    • System audits
    • Leak detection equipment and labor
    • Contractors

    Questions to Ask

    • Do you know who to ask to obtain your “unaccounted for” percentage? (Hint - operations and billing departments are sources for produced and sold water, which can be used to calculate a cursory estimate of unaccounted for water. However, a thorough audit process is needed for a fully substantiated estimate of unaccounted for water.)

    Related Literature

    File:2.12 Food Service Equipment-CSS-2005.pdf


    AWWA (1999), American Water Works Association, “Water Audits and Leak Detection: Manual of Water Supply Practices M 36.”

    Bardsley, A. and R. Lloyd, “Leakage Reduction: A Proven Alternative Resource. A Yorkshire Water Services UK Three Year Study,” AWWA Water Resources Conference Proceedings, 2004.

    California Department of Water Resources (1986), “Water Audit and Leak Detection Guidebook,” with the American Water Works Association California – Nevada Section.

    California Department of Water Resources, “Leak Detection Technology,” Water Conservation News, Spring 2002, URL: http://www.owue.water.ca.gov.

    Farley, M., and S. Trow, “Losses in Water Distribution Networks – A Practitioner’s Guide to Assessment, Monitoring, and Control,” IWA, April 2003.

    Flowers, J., “U.S. Environmental Protection Agency’s Interest in the Water System Leakage Issue,” AWWA Conference Proceedings, 2001.

    Greeley, D.S. (1981), “Leak Detection Productivity,” Reference Number 1981, Water/Emergency & Management, Des Plaines, p. 111 (as noted in AWWA 1990).

    Lalonde, A. “Use of Flow Modulated Pressure Management in York Region, Ontario to Reduce Distribution System Leakage,” AWWA Water Resources Conference Proceedings, 2004.

    Lambert, A., “Issues and Needs in Water Loss Reduction,” AWWA Conference Proceedings, 2001.

    Maddaus, L., J. Van Arsdel, and C. Woody, “Tracking Down Those Water Losses! A Case Study in Asheville North Carolina,” AWWA Water Resources Conference Proceedings, 2004.

    Moyer, E. et al., “The Economics of Leak Detection and Repair,” originally published in Journal AWWA (vol. 75, no. 1, January 1983) as reported in Thorton (2002, p 241).

    Moyer, E.E. (1985), “The Economics of Leak Detection: A Case Study Approach,” American Water Works Association.

    T.K. Rajala, “Kansas Water Plan Programs to Reduce Unaccounted For Water,” AWWA Conference Proceedings, 2001.

    Thorton, J., “Efficient Water Pressure Management as an Effective Tool for Utilities,” AWWA Water Resources Conference Proceedings, 2004.

    Thorton, J., “Water Loss Control Manual,” McGraw-Hill, 2002.

    Trow, S., and M. Farley, “Developing a Strategy for Leakage Management in Water Distribution Systems,” Proceedings of the IWA Conference on Efficiency Use and Management of Urban Water Supply, April 2003.

    Young, A. “Advanced Water Pressure Management in the Berea-Alexander Park Supply District, Johannesburg, South Africa,” published in Thorton (2002, p 279).