Title: Reading and Audio-Visual Assignments
Course: GFM 103 Exterior Environmental Management > Section: GFM 103 Exterior Environmental Management

Reading and Audio-Visual Assignments

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Accounting for Water

Accounting for Water—Accounting for water is an essential step toward ensuring that a water utility is sustainable. This is best accomplished when water systems meter use by their customers. Metering helps to identify losses due to leakage and also provides the foundation on which to build an equitable rate structure to ensure adequate revenue to operate the system.

National Environmental Service Center Tech Brief: Water Meters (PDF) (4 pp., 1,360K, About PDF)

In the “top-down” or preliminary water audit process, apparent losses are frequently quantified first and the real losses are taken as the remaining loss volume after apparent losses and unbilled authorized consumption are subtracted from the total Non-revenue Water Volume. In such cases, errors in under-stating the volume of apparent loss results in real losses being over-stated. It is possible to identify apparent losses through billing data discrepancies or abrupt changes in amounts of water that have been historically used. Some existing billing software packages have built in functionality to flag historical water use changes. Desktop spreadsheet software can also be programmed to flag water use changes with minimal effort. AMR systems that can track and show usage profiles at more than monthly or quarterly billing intervals may also be instrumental in finding either real or apparent losses. Sudden increases in meter readings may be a sign of leakage, unauthorized use, or an open valve that should be closed. Accounts that have been estimated but not read for several billing periods should also be reviewed since the estimated usage may be quite different from the actual usage. It is prudent to re-calculate the apparent loss volumes annually to ensure that water usage patterns in the area have not changed unduly, causing a distortion of the real loss (leakage) volume.

Physically Locating Leaks and Leak Detection Approaches Identifying system leaks can pose a challenge. While operating personnel might identify some leaks in the distribution system during routine field inspections, not all leaks are visible, and targeted leak detection efforts are needed to detect hidden leaks in the water distribution system. Planned maintenance will help identify leak occurrences. To better understand how water leaks are detected, water managers should look at three major water loss leak detection categories:

(1) leak detection through appearance,

(2) leak quantification through flow monitoring, and,

(3) locating hidden leaks with leak detection equipment (acoustic, thermal, electromagnetic, tracer, etc.).