Regulations for onsite treatment and reuse of nonpotable water (SBDDW-22-001)

The regulatory framework establishes technical and operational standards for the design, construction, and operation of onsite treated nonpotable water systems in California, applicable to multifamily, commercial, and mixed-use buildings that reuse graywater, stormwater, or roof runoff. These systems must include comprehensive collection, treatment, storage, and distribution components with rigorous pathogen reduction requirements, such as a UV disinfection dose of at least 160 mJ/cm² for virus reduction or 240 mJ/cm² for protozoa, chlorination with a minimum CT value of 10.0 mg-min/L and a free chlorine residual of 1.0 mg/L, and turbidity limits not exceeding 0.2 NTU for more than 5% of time. Compliance is enforced through continuous process verification using surrogate parameters, mandatory monitoring, and annual reporting, with failure to meet critical limits triggering mandatory incident reporting and re-validation studies. Systems must be equipped with SCADA for real-time oversight, backflow prevention assemblies tested annually by certified professionals, and permanent signage clearly identifying nonpotable water throughout the distribution network. All systems are subject to oversight by local jurisdictions, which are responsible for permitting, inspection, and final acceptance after commissioning, which must conclude with a submitted report within 30 days. Existing systems have up to two years to comply, with possible extensions to five years. Performance deliverables include as-built drawings, operations and maintenance manuals, standard operating procedures, sampling plans, and validation studies. While no contract value, pricing, payment terms, or federal acquisition regulation clauses are applicable, the regulatory structure requires detailed documentation of personnel qualifications, contingency plans for equipment failure or chemical release, and cross-connection control protocols aligned with California Plumbing Code and Health and Safety Code provisions. Submission of required materials follows guidance from the State Water Resources Control Board’s Division of Drinking Water, with annual reports due by February 1st to a designated Sacramento address, and regulatory filings referenced through a public webpage, with technical oversight led by a supervising engineer at the agency.