Regulations for Onsite Treatment and Reuse of Nonpotable Water (SBDDW-22-001)

Status of the Regulations

Staff continues working on the rulemaking package in 2023 while coordinating with stakeholders and partner state agencies. Staff plans to submit the Notice of Proposed Rulemaking to the Office of Administrative Law to start the rulemaking process by late Summer 2024 with a projected board adoption in 2025.


California Water Code section 13558 requires the State Water Board to adopt regulations on or before December 1, 2022, for risk-based water quality standards for the onsite treatment and reuse of nonpotable water for nonpotable end uses in multifamily residential, commercial, and mixed-use buildings.

Water Code section 13558 also requires that on or before December 1, 2023, the Department of Housing and Community Development, in consultation with the State Water Board, is required to develop and propose for adoption any necessary corresponding building standards to support the risk-based water quality standards established by the State Water Board.

Pursuant to Water Code subsections 13558(c) and (d), the risk-based water quality standards will not address untreated graywater systems that are used exclusively for subsurface irrigation and untreated rainwater systems that are used exclusively for surface, subsurface, or drip irrigation.

Existing onsite treated nonpotable water systems in operation before the effective date of the regulations will be required to comply with the regulations within two years of the effective date.

Update to the Proposed Pathogen Control Treatment Trains

The following slides are prepared by DDW staff to address requests from stakeholders to provide an update to the draft requirements related to the proposed pathogen control treatment trains initially presented in the August 1, 2022, staff workshop. Please note that the information provided on these slides are not considered regulations. Formal rulemaking for these regulations will commence in 2024 as described in the Status of Regulations above.

Staff Workshop

A staff workshop for the regulations was held on August 1, 2022. Staff workshop information along with the video recording and presentation slides are available in the links below:

Frequently Asked Questions

State Water Board staff has developed a set of frequently asked questions regarding the regulations. For any questions not addressed in the document, please contact

Rulemaking Information

Information and documentation pertaining to this regulatory action will be provided here, pending development of the regulations.

Sections Affected

To be provided

History of Rulemaking Proceedings

  • Notice of Proposed Rulemaking Published: TBD
  • Close of the 45-Day Public Comment Period: TBD
  • Date of Scheduled Public Hearings: TBD
  • Date filed with Office of Administrative Law: TBD
  • Approved by Office of Administrative Law: TBD

Filed with the Secretary of State: TBD
Effective Date: TBD

Status of Proposal

Staff has not started Rulemaking process

Rulemaking Documentation

To be provided

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For Questions or Comments, please contact:

State Water Board Resolution

Information and documentation pertaining to a Resolution to adopt the proposed regulations will be provided here.