§ 24-344. Definitions.

The following words, terms and phrases, when used in this division, shall have the meanings ascribed to them in this section, except where the context clearly indicates a different meaning:

Atmospheric vacuum breaker means a backflow prevention device which is operated by atmospheric pressure in combination with the force of gravity. The unit is designed to work in a vertical plane only. The moving part consists of a poppet valve, which must be carefully sized to slide in a guided chamber and effectively shut off the reverse flow of water when a negative pressure exists.

Auxiliary water supply means any water supply on or available to the premises other than the purveyor's approved public potable water supply. These auxiliary water supplies may include water from another purveyor's public potable water supply or any natural source(s) such as a well, spring, river, harbor, etc., or "used waters" or industrial fluids." These waters may be polluted, contaminated, or may be objectionable and constitute an unacceptable water source over which the water purveyor does not have sanitary control.

Back pressure means the reversal of normal flow in a system due to an increase in the downstream pressure which is greater than the supply pressure. Back pressure is created whenever the downstream pressure exceeds the supply pressure. This is possible in installations such as heating systems, elevated tanks, pumps which malfunction by pumping backward, etc. An example would be an open valve on a supply line to a boiler operating at 100 pounds of pressure at the same time that the pressure in the county water main was below such pressure. As water tends to flow in the direction of least resistance, a back pressure condition would be created and the contaminated boiler water would flow into the potable water supply.

Back siphonage means the reversal of normal flow in a system caused by a negative pressure (vacuum or partial vacuum) in the supply piping. Back siphonage can be created when there is a reduction of pressure in the water supply due to nearby firefighting, repairs or breaks in the county water main, etc. The effect is similar to sipping soda by inhaling through a straw, which induces a flow in the opposite direction.

Backflow means the reversal of the normal direction of flow in water service lines. This reversal of flow can result in contamination of the public potable water supply if there is an unprotected cross connection in a customer's internal plumbing system. There are two causes of backflow; back pressure and back siphonage.

Backflow prevention device means a device to counteract back pressure or prevent back siphonage.

Backflow prevention device approved means the term approved backflow prevention device shall mean a device that has met the requirements of one or more of the following standards:

(a)	AWWA C-506	Standard for backflow prevention devices, reduced pressure principle and double check valve types
(b)	ASSE 1001	Atmospheric type vacuum breakers
(c)	ASSE 1011	Hose connection vacuum breakers
(d)	ASSE 1020	Pressure type vacuum breakers
(e)	ASSE 1024	Dual check type backflow preventer (Residential Use Only)
(f)	ASSE 1013	Reduced pressure principle back pressure backflow preventers
(g)	ASSE 1015	Double check valve type back pressure backflow preventers
(h)	USC FCC	University of Southern California Foundation for cross-connection control and hydraulic research

 

Containment means protection of the public potable water supply by installation of an approved backflow prevention device in the customer's water service line which would prevent the reversal of flow from the service line into the public water supply.

Contaminant means any foreign substance that degrades the quality of the public potable water supply or may create a health hazard.

Cross connection means a direct arrangement of a piping line which allows the potable water supply to be connected to a line which actually contains, or might potentially contain, a contaminant or pollutant. Any physical arrangement whereby a public water supply system is connected, directly, or indirectly, with any other water supply system, sewer, drain, conduit, pool, storage reservoir, plumbing fixture or other device or facility which contains or may contain contaminated or polluted water, industrial fluids, sewage or other waste or liquid of unknown or unsafe quality, which may be capable of imparting contamination or pollution to the public water supply system as a result of backflow. An example would be a common garden hose attached to a hose bib with the end of the hose lying in a sink used for mixing pesticides. Other examples include, but are not limited to; bypass arrangements, jumper connections, removable sections, swivel or change-over devices, or any other temporary or permanent devices or facilities through which or because of which backflow could occur.

Double check valve assembly means an assembly composed of two single, independently acting check valves, including tightly closing shutoff valves located at each end of the assembly and suitable connections for testing the water tightness of each check valve.

Fire line means any dedicated line which feeds a fire protection sprinkler system.

Health hazard means any condition, devices, or practices in any water supply system, or in its operations, which create or may create a danger to the health and well-being of the water customer.

Industrial fluids means any fluids or solution that may be chemically, biologically or otherwise contaminated or polluted in a form or concentration that would constitute a health, system, pollution or plumbing hazard if introduced into the public potable water system. These may include but shall not be limited to; polluted or contaminated water; all types of process waters and used water originating from the public potable water system that may have deteriorated in sanitary quality; chemicals in fluid form; plating acids and alkalis; circulating cooling waters connected to an open cooling tower; or cooling towers that are chemically or biologically treated or stabilized with toxic substances; contaminated natural waters, such as wells, springs, streams, etc.; oils, gases, glycerin, paraffins, caustic and acid solutions; and other liquid and gaseous fluids used in industrial or other purposes, including firefighting purposes.

Isolation means protection of the customer's internal plumbing system by the installation of devices to prevent backflow from potentially hazardous cross connections.

Pollutant means any foreign substance in water that tends to degrade its quality so as to constitute a non-health hazard or impair the usefulness of the water, or any chemical, matter or material that may change the color of, or add odor to the water.

Pressure vacuum breaker means a pressure vacuum breaker is similar to an atmospheric vacuum breaker except that the checking unit "poppet valve" is activated by a spring. This type of vacuum breaker does not require a negative pressure to react and can be used on the pressure side of a valve.

Public water supply means any system or water supply intended or used for human consumption or other domestic use, including source, treatment, storage and distribution where water is furnished to any community, collection or number of individuals, or is made available to the public for human consumption or domestic use, but excluding supplies serving one single-family residence.

Reduced pressure principle backflow prevention device means a device incorporating two or more check valves and an automatically operating differential relief valve located between the two check valves, two shutoff valves and equipped with necessary appurtenances for testing. The device shall operate to maintain the pressure in the zone between the two check valves, less than the pressure of the public water supply side of the device even at cessation of normal flow. In case of leakage of each check valve, the differential relief valve shall operate to maintain this reduced pressure by discharging to the atmosphere. When the inlet pressure is two pounds per square inch or less, the relief valve shall open to the atmosphere, thereby providing an air gap in the device. This air gap shall also be above the 100-year flood level.

( Ord. No. 16-16 , § 1, 9-6-16)