California Code, Water Code - WAT § 14877.3

(a) Subject to subdivision (b), a city, county, or other local agency may adopt, after a public hearing and enactment of an ordinance or resolution, building standards that are more restrictive than the graywater building standards adopted pursuant to state requirements.

(b) An ordinance adopted pursuant to subdivision (a) shall include the local climatic, geological, topographical, or public health conditions that necessitate building standards that are more restrictive than the graywater building standards adopted pursuant to state requirements and shall be limited to the specific area of the city, county, or local agency where the conditions exist.

(c) Prior to commencing the issuance of permits for indoor graywater systems pursuant to state requirements relating to graywater, a city, county, or other local agency shall seek consultation with the local public health department to ensure that local public health concerns are addressed in local standards or ordinances, or in issuing permits.