What is California SB 555?
California SB 555 is a 2015 state law that requires urban retail water suppliers to complete and submit validated water loss audits every year, using the AWWA M36 method and the AWWA Free Water Audit Software. It also set the basis for state water loss performance standards, making measured loss data a regulatory requirement.
What it is
Before SB 555, many suppliers reported losses inconsistently. The law standardized the method and required each audit to be validated by a qualified validator before submission to the Department of Water Resources.
Annual submissions began in October 2017. Validation checks that each input is supported by evidence and that data validity grades are reasonable, which means suppliers need records, not estimates.
The law also directed the State Water Resources Control Board to adopt performance standards for water loss, which moves the focus from reporting losses to reducing them.
Who it applies to
Urban retail water suppliers in California above the size threshold set in state law. Check the Department of Water Resources and the State Water Resources Control Board for current deadlines, validation requirements and performance standards.
What evidence it needs
A validated audit needs evidence for each input in the water balance.
- Source meter volumes and meter accuracy testing
- Billing data for authorized consumption
- Documented estimates for unbilled and unmetered use
- Validation records and data validity grades
How Aqueduct helps
Aqueduct keeps the audit inputs measured and current, so validation is a check rather than a reconstruction.
- aQ WaterGuard volumes per district measured all year, not gathered at year end
- Night flow baselines that locate real losses before the audit is due
- Data quality checks that flag missing reads and drifting meters
- aQ Assurance exports for the supplier and its validator