On April 22, 2026, the State Water Resources Control Board published new regulations essentially banning NSF-350 CII on-site greywater treatment systems due to their health and safety failings. ReWater’s on-site untreated greywater irrigation systems are specifically exempt (Water Code Section 13558(c)).
This action was a result of SB966 in 2019, now codified in Water Code Section 13558 et seg, and years of hearings, with the new regulations found in Title 22 sections beginning at CCR §60600 through §60710.
The regulations are retroactive and de facto nullify all NSF-350 certifications, local ordinances, issued building permits, and any other previous authorizations for greywater treatment systems.
New as well as previously permitted, installed, signed off, and/or operational NSF-350 certified CII greywater treatment systems are now 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 was a proven failure and is no longer accepted.
Automatically shut down and divert to sewer when a LRT failure is detected. NSF-350 systems systemically fail due to tiny filters that clog easily, live membranes that die from chlorine bleach and surfactant overloads, UV lights that burn out randomly, Ozone generators that can’t handle water vapor, dust, or heat, and pumps that aren’t robust enough. LRT’s are common.
Undergo bi-monthly water testing for the life of the system. Testing tells the owner when the system isn’t working and needs repair or maintenance, though the stench is usually their first clue.
Have bi-annual maintenance contracts with a certified professional for the life of the system. This professional is usually an engineer.
Have a professional test and re-certify the system annually and report its current status to the State Water Resources Control Board annually. This professional is an engineer.
Operation and maintenance contract recorded as a deed covenant with the County Registrar. The system is a permanent part of the building and new owners need to know their responsibilities and liabilities.
Pay fines for non-compliance. Though existing systems are given two years to comply, no NSF-350 system has come even close to ~5-log virus or ~4-log protozoa reduction. It’ll take a whole new process to comply.
And you thought the purchase price of a NSF-350 system was outrageous…