A water audit is an accounting procedure. The purpose of a water audit is to accurately determine the amount of unaccounted-for water (UAW) in a water distribution system. UAW is calculated from verified supply and consumption records, factoring in various estimated usage figures. Due to potential short-term inaccuracies, a water audit generally considers data from the most recent 12-month period. Any period less than 12 months will not reflect seasonal climatic and population variations. Detailed guidance for conducting a water audit can be found in the American Water Works Association's (AWWA) Manual #36; Water Audits and Leak Detection. The forms found in this manual are also acceptable for the purpose of documenting a water audit.

The results of a water audit can be considered valid only if the figures used to calculate the level of UAW are accurate. The production and consumption figures used to calculate UAW come from metering data, which is dependent upon meter accuracy. Because of this, meter accuracy testing is an essential part of a water audit. The AWWA provides testing guidelines in Manual #6; Water Meters: Selection, Installation, Testing, and Maintenance. As a general rule, all source meters should be verified annually. A representative sample of service meters (1%-5%) should be bench- or field-tested during the water audit. In calculating UAW, supply and consumption figures can be adjusted up or down according to meter accuracy rates. It should be noted that inaccurate service meters usually under-register. The level of UAW can be adjusted to compensate for service meter under-registration. To comply with the Southwest Florida Water Management District's Water Use Caution Area (WUCA) Public Supply Special Conditions, all public supply water use permit holders with permits for 100,000 gallons per day and greater, geographically located within a WUCA, must conduct periodic water audits.

All public supply permittees with permits for 100,000 gallons per day and greater in Water Use Caution Areas (WUCA) are required to perform periodic water audits.

Download the Water Audit Worksheet

in Microsoft Excel format


Submit completed worksheets to:

Attention: Permits Data Section
Southwest Florida Water Management District
2379 Broad Street
Brooksville, Florida 34609-6899

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