California Code, Health and Safety Code - HSC § 116290

Before August 6, 1998, in areas where the water service rendered by a person is primarily agricultural, and domestic service is only incidental thereto, this chapter shall not apply except in specific areas in which the department has found its application to be necessary for the protection of the public health and has given written notice thereof to the person furnishing or supplying water in the area.

The department may prescribe reasonable and feasible action to be taken by those persons or the users to insure that their domestic water will not be injurious to health.