Freeman

Appellants are the owners of residences in the City of Concord served by the water system of respondent Contra Costa County Water District. Each of the appellants maintains on his property a well from which water is drawn for such purposes as gardening and car-washing. Although appellants had not connected their well water systems to the pipes of the district’s public system, the district threatens to terminate service until the affected householders agree to have installed, at their own expense, a “double check valve assembly,” designed to prevent water from the auxiliary supply from “backing up” into and contaminating the public water supply. Appellants sought from the court protection against the district’s threat; judgment was for the district, and the present appeal followed. We affirm the judgment.

The record shows without contradiction that contamination of a water system can occur if there is a physical connection between the public system and auxiliary water supply, such as where the two. systems are connected by pipes, or where the auxiliary water is “impounded” (e.g., in a swimming pool or fish pond) and an ordinary garden hose from the public water supply is…