On April 22, 2026, the State Water Resources Control Board published new regulations essentially banning NSF-350 and other on-site greywater “treatment” systems due to their health and safety problems. ReWater’s systems for untreated greywater are specifically exempt (Water Code Section 13558(c)).
These new regulations are a result of SB966 in 2021 and are now codified in Water Code Section 13558 et seg. They are retroactive and de facto nullify all NSF-350 and other certifications, local ordinances, issued building permits, and any other authorization for greywater treatment systems.
New as well as previously permitted, installed, signed off, and operational NSF-350 certified greywater treatment systems will be required to:
Be tested on-site and certified by a professional to hit ~5-log virus and ~4-log protozoa Log Reduction Targets (LRT). Lab testing is no longer acceptable.
Automatically shut down and divert to sewer when a LRT failure is detected. Because these systems are known to systemically fail due to numerous real-world issues with real greywater.
Undergo bi-monthly water testing for the life of the system, to tell the owner when the system isn’t working
Have bi-annual maintenance contracts with a professional for the life of the system. Have a professional re-certify the system annually and report it to the State Water Resources Control Board annually.
Operation contract recorded as a deed covenant with the County Registrar
Pay fines for non-compliance.
The law gives existing systems two years to comply, but no NSF-350 system has come even close to ~5-log virus or ~4-log protozoa reduction.