Tariff Rule 16

Mark III also cites each Defendant's Tariff Rule 16C, which requires a user who employs a pump to increase the pressure of water received from the utility's main or service connection to do so only through a backflow prevention arrangement approved by the utility. At the time the complaint was filed, each Defendant's Rule 16C contained the following exception:

This requirement shall not apply to American Water Works Association Class 2 fire protection systems, except as provided for in the Information Bulletin issued by the Office of the State Fire Marshal on December 10, 1984.⁸

On June 29, 2000, three weeks after the complaint was filed, Defendant SoCal Water filed an advice letter revising Rule 16C to require approved backflow protection devices on all fire services (including hydrants and fire sprinklers), and additionally, on all commercial, industrial and institutional water services, and it subsequently incorporated the new requirement into its defense against Mark III's complaint. Two weeks later, on July 14, 2000, it filed a second advice letter strengthening that requirement, clarifying how it would be applied to existing versus new fire services, and deleting the Rule 16C exception for Class 2 fire protection systems quoted above. The basis on which SoCal Water was able to get those advice letter filings accepted and into its tariffs is the subject of a separate inquiry outside of this complaint proceeding.

Both Defendants still have in their tariffs the following provision in Rule 16C(2), Backflow Preventers Required:

The utility will evaluate the degree of potential health hazard to the public water supply which may be created as a result of conditions existing on a user's premises. As a minimum, the evaluation will consider: The existence of cross-connections, the nature of materials handled on the property, the probability of a backflow occurring, the degree of piping system complexity and the potential for piping system modification.

This wording echoes CCR, Title 17, Section 7585. It once again underscores that both Defendants must consider the specific conditions on a user's premises in deciding whether backflow protection is needed, and if so, what type, and that there is a minimum set of factors they must evaluate in doing so.