In 2003, the drought-stricken state of Texas passed a law requiring retail public water utilities to conduct a water audit every five years.

“We needed to know water loss accountability, how much water loss there is, how the utilities report water losses, and how efficient they are in doing so,” says Mark Mathis, municipal water specialist for the Texas Water Development Board.

Three years after the program was implemented, though, Mathis is hard-pressed to compare water loss volumes in the state. Each of its more than 3000 utilities had its own method for calculating water loss percentages, with different variables. Nothing was standardized. “It's so across the board,” he says.

These inconsistencies will gradually disappear as utilities adopt the state's new water audit methodology. As part of the state mandate, the water board created an audit form and worksheet based on a newly formulated International Water Association (IWA)/American Water Works Association (AWWA) audit process. In an attempt to make utilities account for every single drop of water, the audit standardizes terminology in an industry where there are no hard-and-fast definitions.

“It's a new method that eliminates the percentage method of accounting, as well as the term ‘unnaccounted-for' water, to show in more exact terms where the inefficiencies are occurring,” says Mathis.

Although the board is non-regulatory, it can deny funding requests from utilities that haven't submitted a water audit. Mathis believes this stipulation will increase the number of local utilities that adopt the new methodology, so the board can better calculate and manage the state's water loss.


How do you report water loss? What factors do you use to calculate water loss percentages?

Chances are, if 100 water utilities are asked such questions, most won't agree on any given answer. For example, most utilities consider a 10% to 15% “unaccounted-for” water loss rate as acceptable. But what is “unaccounted-for” water loss?

“You can put 10 water utility managers in a room, ask them what ‘unaccounted-for' is, and they will each have a different answer,” says Mathis.

There also isn't a uniform method for determining water loss percentages, says Mathis. Plus, there are four key measures percentages don't reveal:

  • Where the losses are occurring
  • How much those losses are costing the utility
  • How much is being lost (expressed in volume)
  • Why the losses are occurring.