State Water Board adopts on-site nonpotable reuse regulations required by SB 966
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Summary
The board adopted risk-based statewide regulations implementing SB 966 to govern building-scale on-site treatment and reuse of nonpotable water, setting pathogen log-reduction criteria, an implementation timeline for rulemaking (OAL package due by 03/21/2026) and delegating permitting authority to local jurisdictions.
The State Water Resources Control Board voted to adopt proposed regulations establishing statewide criteria for on-site treatment and reuse of nonpotable water, fulfilling requirements of Senate Bill 966.
Staff said the risk-based regulations focus on building-scale installations in urban settings, provide prescriptive pathogen log-reduction treatment trains for indoor and certain outdoor uses, and are intended to complement — not replace — Title 22 recycled-water ("purple pipe") rules. Shirley Rosalella (technical lead) and Randy Barnard (staff presenter) explained that the regulations cover graywater, roof runoff, stormwater and on-site wastewater in specified end uses and that local jurisdictions will have primary implementation responsibility under the statute.
Staff described the regulatory development process: an expert panel convened by the National Water Research Institute set pathogen log-reduction targets, peer review was completed, and the formal rulemaking began after publication in the California Notice Register on 03/21/2025. Staff said they received 18 comment letters during the initial 45-day comment period and 6 letters during a required 15-day period after revisions; some revisions were made to streamline alternative treatment approvals, add notification requirements for water and sewer providers during commissioning/decommissioning, and allow flexibility in signage and labeling.
Public commenters — including industry groups, technology firms and environmental organizations — raised concerns about unintended effects on stormwater capture and the cost of compliance for certain industrial or off-site capture projects. Staff and the board repeatedly clarified that the regulations are narrowly focused on building-scale on-site reuse and are not intended to apply to typical landscape infiltration or broader regional stormwater-capture projects; staff noted ongoing work to address mixed-source and off-site capture projects in separate forums.
The board unanimously adopted the regulations by roll-call vote. Staff described next steps: Department of Finance review, submission of the rulemaking package to the Office of Administrative Law (OAL) with a projected effective date in March 2026, and guidance for local jurisdictions and coordination with the California Building Standards Commission and Housing and Community Development for building-code integration.