(a) No water service connection to any premises shall be installed or maintained by the city unless the water supply is protected as required by Sections 7583 through 7605 of Title 17 of the California Administrative Code (1984), or other relevant state laws and regulations. The city shall discontinue service of water to any premises in the following situations: if a backflow prevention device required by this code is not installed, tested and maintained; if a backflow prevention device has been removed or by-passed; or if an unprotected cross-connection exists on the premises. Service will not be restored until such conditions or defects are corrected.
(b) The user's system should be open for inspection at all reasonable times to authorized representatives of the city to determine whether cross-connections or other structural or sanitary hazards, including violations of this code and state laws and regulations, exist. When a hazardous condition becomes known, the public works director may deny or immediately discontinue service to the premises by providing for a physical break in the service line until the user has corrected the condition(s) to the satisfaction of the public works director.
(c) An approved backflow prevention device shall also be installed on each service line to a user's water system at or near the property line before the first branch line leading off the service line, wherever the following conditions exist:
(1) In the case of premises having an auxiliary water supply which is not, or may not be, of safe bacteriological or chemical quality and which is not acceptable as an additional source by the public works department, the public water system shall be protected against backflow from the premises by installing a backflow prevention device in the service line appropriate to the degree of hazard.
(2) In the case of premises on which any industrial fluids or any other objectionable substances are handled in such a fashion as to create actual or potential hazard to the public water system, the public system shall be protected against backflow from the premises by installing a backflow prevention device in the service line appropriate to the degree of hazard. This shall include the handling of process waters and waters originating from the city system which have been subject to deterioration in quality.
(3) In the case of premises having (i) internal cross-connections that cannot be permanently corrected and controlled, (ii) intricate plumbing and piping arrangements, or (iii) systems where entry to all portions of the premises is not readily accessible for inspection purposes, so that it is impracticable or impossible to ascertain whether or not dangerous cross-connections exist, the public water system shall be protected against backflow from the premises by installing a backflow prevention device in the service line.
(d) The type of protective device required under subsections (c)(l), (2) and (3) shall depend upon the degree of hazard which exists as follows:
(1) In the case of any premises where there is an auxiliary water supply, as stated in subsection (c)(l) of this section, which is not covered by subsections (d)(2) through (10) which follow, the public water system shall be protected by an approved air-gap separation or an approved reduced pressure principle backflow prevention device.
(2) In the case of any premises where there is water or substance that would be objectionable but not hazardous to health if introduced into the public water system, the public water system shall be protected by an approved double check valve assembly.
(3) In the case of any premises where there is any material dangerous to health which is handled in such a fashion as to create an actual or potential hazard to the water system, the city water system shall be protected by an approved air-gap separation or an approved reduced pressure principle backflow prevention device. Examples of premises where these conditions will exist include, but are not limited to, sewage treatment plants, sewage pumping stations, chemical manufacturing plants, hospitals, mortuaries and plating plants.
(4) In the case of any premises where there are “uncontrolled” cross-connections, either actual or potential, the city water system shall be protected by an approved air-gap separation or an approved reduced pressure principle backflow prevention device at the service connection.
(5) In the case of any premises where, because of security requirements or other prohibitions or restrictions, it is impossible or impractical to make a complete in-plant cross-connection survey, the city water system shall be protected against backflow or back-siphonage from the premises by the installation of a backflow prevention device in the service line. In this case, maximum protection will be required; that is, an approved air-gap separation or an approved reduced pressure principle backflow prevention device shall be installed in each service line to the premises.
(6) In the case of premises with cross-connections to sewage lines, pumps, flushers, etc., the city water system shall be protected by an approved air-gap separation or an approved reduced pressure principle backflow prevention device.
(7) In the case of Tanker and Spray Tanks of 49 gallons or more, air-gap separation or an approved reduced pressure principle backflow prevention device is required.
(8) In the case of any premises with a Class III or IV fire protection system, the city water system shall be protected by a double check detector check with a meter protected by a double check valve assembly.
(9) In the case of any premises with a Class V or VI fire protection system, the city water system shall be protected by an approved air-gap or an approved reduced pressure principle device.
(10) In the case of commercial and industrial buildings, the city water system shall be protected by, at a minimum, an approved double check value assembly on each service connection. An approved air-gap or reduced pressure principle device will be required if, in the opinion of the public works director, the degree of hazard so requires.
(e) Any backflow prevention device required herein shall be of a model and size approved by the public works department. The term “approved backflow prevention device” shall mean a device which has been manufactured in full conformance with the standards established by the American Water Works Association entitled:

AWWA C506-78 Standards for Reduced Pressure Principle and Double Check Valve Backflow Prevention Devices
and which has met completely the laboratory and field performance specifications of the Foundation for Cross-Connection Control and Hydraulic Research of the University of Southern California. The AWWA and FCCC & HR standards and specifications have been adopted by the city and the most current specifications are on file in the public works department. Final approval shall be evidenced by a “Certificate of Approval” issued by an approved testing laboratory certifying full compliance with said AWWA standards and FCCC&HR Specifications.
(f) It shall be the duty of the city at any premises where backflow prevention devices are installed to have certified inspections and operational tests made at least once per year. In those instances where the public works director deems the hazard to be great enough, certified inspections may be required at more frequent intervals. These inspections and tests shall be at the expense of the user and shall be performed by a certified tester approved by the public works director. It shall be the duty of the public works director to see that these timely tests are made. These devices shall be repaired, overhauled or replaced at the user's expense whenever said devices are found to be defective. Records of such tests, repairs, and overhaul shall be kept.
(g) All presently installed backflow prevention devices which do not meet the requirements of this section but were approved devices for the purposes described herein at the time of installation and which have been properly maintained, shall, except for the inspection and maintenance requirements under paragraph (f) of this section, be excluded from the requirements of these rules so long as the public works director is assured that they will satisfactorily protect the city water system. Whenever the existing device is moved from the present location or requires more than minimum maintenance or constitutes a hazard to health, the unit shall be replaced by a backflow prevention device meeting the requirements of this section at the expense of the user. (Ord. No. 1113, § 4 (part).)