California Code, Water Code - WAT § 73503

(a) The city, in consultation with the association and the offices of emergency services in Alameda County, Santa Clara County, and San Mateo County, shall prepare an emergency response plan describing how water service will be restored to the area served by the bay area regional water system after an interruption caused by earthquake or other natural or manmade catastrophe, and thereafter shall be implemented.

(b) During any interruption in supply caused by earthquake, or other natural or manmade catastrophe, a regional wholesale water supplier shall distribute water to customers on an equitable basis, to the extent feasible given physical damage to the regional water system, without preference or discrimination based on a customer's geographic location within or outside the boundary of the regional wholesale water supplier.