California Code, Health and Safety Code - HSC § 114211

(a) The water system shall be designed and constructed using materials that enable water to be introduced without contamination.

(b) All tanks, line couplings, valves, and all other plumbing shall be designed, installed, maintained, and constructed of materials that will not contaminate the water supply, food, utensils, or equipment.

(c) All waste lines shall be connected to wastewater tanks with watertight seals.

(d) Any connection to a wastewater tank shall preclude the possibility of contaminating any food, food-contact surface, or utensil.