California Code, Health and Safety Code - HSC § 17922.12

(a) For the purposes of this section, “graywater” means untreated wastewater that has not been contaminated by any toilet discharge, has not been affected by infectious, contaminated, or unhealthy bodily wastes, and does not present a threat from contamination by unhealthful processing, manufacturing, or operating wastes. “Graywater” includes wastewater from bathtubs, showers, bathroom washbasins, clothes washing machines, and laundry tubs, but does not include wastewater from kitchen sinks or dishwashers.

(b) Notwithstanding Chapter 22 (commencing with Section 14875) of Division 7 of the Water Code, at the next triennial building standards rulemaking cycle that commences on or after January 1, 2009, the department shall adopt and submit for approval pursuant to Chapter 4 (commencing with Section 18935) of Part 2.5 building standards for the construction, installation, and alteration of graywater systems for indoor and outdoor uses.

(c) In adopting building standards under this section, the department shall do all of the following:

(d) The department may revise and update the standards adopted under this section at any time, and the department shall reconsider these standards at the next triennial rulemaking that commences after their adoption.

(e) The approval by the California Building Standards Commission of the standards for graywater systems adopted under this section shall terminate the authority of the Department of Water Resources to adopt and update standards for the installation, construction, and alteration of graywater systems in residential buildings pursuant to Chapter 22 (commencing with Section 14875) of Division 7 of the Water Code.