Water Loss Standard

The Basics

  • The water loss standard is derived from separate but related legislation, Senate Bill 55 (2015), which also requires urban water retail suppliers to submit annual validated water audit.
  • The water standard focuses on real losses expressed in gallons per connection per day or gallons per mile (of pipe) per day depending on supplier size.  The vast majority of suppliers will have a standard in gallons per connection per day.
  • Supplier specific 2028 water loss targets (maximum loss) are calculated from a State Water Resource Control Board created economic model (link to the create model version below) that incorporates both water loss and economic metrics.
  • The majority of the economic model’s inputs can be customized by supplier if documentation is submitted.  However not all inputs are weighted equally in the model.  Additional information on model inputs can be found below:


August 2021

The updated economic model was released in April 2021. The SWRCB is encouraging water suppliers to customize the inputs and submit to SWRCB staff for approval an updated 2028 target. Formal rulemaking is expected to start in Fall 2021.

Economic model found here.

Timeline of Events

  • April 15 – Revised draft economic model and performance standards
  • Ongoing discussions:
    • CMUA Compliance Path – >30% reduction
    • Changes to economic model
  • Fall? – Formal Rulemaking w/ 45 public comment period
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