California Civil Code > Civil Code §1101.7. Properties Exempt from Water Conservation Requirements
This article shall not apply to any of the following:
(a) Registered historical sites.
(b) Real property for which a licensed plumber certifies that, due to the age or configuration of the property or its plumbing, installation of water-conserving plumbing fixtures is not technically feasible.
(c) A building for which water service is permanently disconnected.