A. "Air gap" means the unobstructed vertical distance through the free atmosphere between the lowest opening from any pipe or faucet supplying water to a tank, plumbing fixture, or other device and the flood-level rim of said vessel. An approved air gap shall be at least double the diameter of the supply pipe, and in no case less than one inch.

B. "Approved" means accepted by the director of public works and utilities and chief operator as meeting an applicable specification stated or cited in this chapter.

C. "Auxiliary water supply" means any water supply on or available to the premises other than the water supplier approved public potable water supply. These auxiliary waters may include water from another supplier’s public potable water supply or any natural source(s) such as a well, spring, river, stream, harbor, etc., or "used waters" or "industrial fluids." These waters may be polluted or contaminated, or they may be objectionable and constitute an unacceptable water source over which the water supplier does not have sanitary control. Any well will be considered as an auxiliary supply unless abandoned to city standards.

D. "Backflow" means the flow of water or other liquids, mixtures or substances under pressure into the distributing pipes of a potable water supply system from any source or sources other than its intended source.

E. "Back-siphonage" means the flow of water or other liquids, mixtures or substances into the distributing pipes of a potable water supply system from any source other than its intended source, caused by the sudden reduction of pressure in the potable water supply system.

F. "Backflow preventer" means an approved device or means designed to prevent backflow or back-siphonage listed in the University of Southern California (USC) Foundation for Cross-Connection Control and Hydraulic Research List of Approved Backflow Prevention Assemblies.

G. "Certified tester" means a tester accepted by the public works and utilities director and chief operator as meeting applicable requirements stated or cited in this chapter.

H. "Contamination" means an impairment of the quality of the potable water by sewage, industrial fluids or waste liquids, compounds or other materials to a degree which creates an actual hazard to the public health through poisoning or through the spread of disease.

I. "Cross-connection" means any physical connection or arrangement of piping or fixtures between two otherwise separate piping systems, one of which contains potable and the other nonpotable water or industrial fluids of questionable safety, through which, or because of which, backflow or back-siphonage may occur into the potable water system. A water service connection between a public potable water distribution system and a customer’s water distribution system which is cross-connected to a contaminated fixture, industrial fluid system, or with a potentially contaminated supply or auxiliary water system constitutes one type of cross-connection. Other types of cross-connections include connectors such as swing connections, removable sections, four-way plug valves, spools, dummy sections of pipe, swivel, or charge-over devices, sliding multiport type, solid connections, etc.

J. Cross-Connections, Controlled. "Controlled cross-connections" means a connection between a potable water system and a nonpotable water system with an approved backflow-prevention device properly installed that will continuously afford the protection commensurate with the degree of hazard.

K. "Cross-connection control by containment" means the installation of an approved backflow-prevention device at the water service connection to any customer’s premises where it is physically and economically infeasible to find and permanently eliminate or control all actual or potential cross-connections within the customer’s water system; or it means the installation of an approved backflow-prevention device on the service line leading to and supplying a portion of a customer’s water system where there are actual or potential cross-connections which cannot be effectively eliminated or controlled at the point of cross-connection.

L. "Customer" means any person or organization who receives water from the city water distribution system.

M. "Director of public works and utilities" means the director of public works of the city.

N. "Chief operator" means the person who has overall responsibility for the day-to-day, hands-on operation of a water treatment facility or the person who has overall responsibility for the day-to-day, hands-on operation of a distribution system and is defined in CCR Title 22, Chapter 1, Section 63750.25.

O. "Double check-valve assembly" means an approved assembly of two independently operating approved check valves with tightly closing shutoff valves on each side of the check valves. The entire assembly shall meet the design and performance specifications and approval of a recognized and city-approved testing agency for backflow-prevention devices. To be approved, these devices must be readily accessible for in-line maintenance and testing and installed to city standards.

P. "Double detector check-valve assembly" means an approved assembly of two independently operating approved check valves with tightly closing shutoff valves on each side of the check valves, plus properly located test cocks for testing of each check valve and a bypass meter. The entire assembly shall meet the design and performance specifications and approval of a recognized and city-approved testing agency for backflow-prevention devices. To be approved, these devices must be readily accessible for in-line maintenance and testing and installed to city standards.

Q. "Fire systems" means a firefighting system with a direct connection to the public potable water system that should be protected in a manner commensurate with the hazard. Fire protection systems may be classified as follows:

R. "Degree of hazard" means the elevation of the potential risk to public health and the adverse effect of the hazard upon the potable water system as:

S. "Industrial fluids system" means any system containing a fluid or solution which may be chemically, biologically, or otherwise contaminated or polluted in a form or concentration such as would constitute a health, system, pollutional or plumbing hazard if introduced into an approved water supply. This may include, but not be limited to: polluted or contaminated waters; all types of process waters and "used waters" originating from the public potable water system which may have deteriorated in sanitary quality; chemicals in fluid form; plating acids and alkalis; circulating cooling waters connected to an open cooling tower and/or cooling towers that are chemically or biologically treated or stabilized with toxic substances; contaminated natural waters such as from wells, springs, streams, rivers, bays, harbors, seas, irrigation canals or systems, etc.; oils, gases, glycerine paraffins, caustic and acid solutions, and other liquid and gaseous fluids used for industrial or other purposes or for firefighting purposes.

T. "Pollution" means the presence of any foreign substance (organic, inorganic or biological) in water which tends to degrade its quality so as to constitute a hazard or impair the usefulness or quality of the water to a degree which does not create an actual hazard to the public health, but which does adversely and unreasonably affect such waters for domestic use.

U. "Reduced pressure principle device" means an assembly of two independently operating approved check valves with an automatically operating differential relief valve between the two check valves, tightly closing shut-off valves on either side of the check valves, plus properly located test cocks for testing of the check and relief valves. The entire assembly shall meet the design and performance specifications and approval of a recognized and city-approved testing agency for backflow-prevention assemblies. The device shall operate to maintain the pressure in the zone between the two check valves at a level less than the pressure on the public water supply side of the device. In case of leakage of either of the check valves, the differential relief valve shall open to the atmosphere. To be approved, these devices must be readily accessible for in-line maintenance and testing and be installed according to city standards.

V. Water, Nonpotable. "Nonpotable water" means water which is not safe for human consumption or which is of questionable potability.

W. Water, Potable. "Potable water" means any water which, according to recognized standards, is safe for human consumption.

X. "Water service connection" means the terminal end of a service connection from the public potable water system; i.e., where the water supplier loses jurisdiction and sanitary control over the water at its point of delivery to the customer’s water system. If a meter is installed at the end of the service connection, then the service connection shall mean the downstream end of the meter. There should be no unprotected takeoffs from the service line ahead of any meter or backflow-prevention device located at the point of delivery to the customer’s waste system. Service connection shall also include water service connection from a fire hydrant and all other temporary or emergency water service connections from the public potable water system.

Y. Water, Used. "Used water" means any water supplied by a water supplier from a public potable water system to a consumer’s water system after it has passed through the point of delivery and is no longer under sanitary control of the water supplier.