Stated in writing by the authority / agency having jurisdiction as being approved.

A sub-atmospheric pressure condition caused by an increase of velocity in a water line through a localized restriction causing a vacuum.

American Society of Sanitary Engineering

A device, which contains a float check (poppet), a check seat and an air inlet vent. When water pressure is reduced to a gauge pressure of zero or below, the float drops, allowing air to enter the device, preventing backsiphonage. Designed to protect against backsiphonage only.

Any water supply on or available to a premise other than the approved water supply.

American Water Works Association

The flow of water or other liquids, gases, mixtures, solids, or substances from any source back into the distribution piping of a potable water supply system.

A device / assembly or means to prevent backflow into the potable water supply.

A backflow preventer, which is designed to be in-line, tested and repaired; an assembly consists of the backflow unit, two resilient seated shut-off valves, and properly located test cocks.

A backflow preventer, which is not designed to be tested and repaired in-line.

Water pressure, which exceeds the operating pressure within the potable water supply.

Backflow due to a reduction in system pressure.

A loop of pipe rising at least 35ft at its upper most point, above the highest point on the downstream piping.

A drain, which provides adequate drainage to a vault with an unobstructed drainpipe.

On the other hand, capillary attraction – is an energy that can cause a liquid to adhere to internal walls of a small pipe overcoming the internal cohesion of the liquid. A form of backflow where liquids can be drawn into small openings of a water outlet.

A person who has shown competence to test backflow assemblies to the satisfaction of the certifying authority.

Any space having limited means for entry / exit and is not designed for continuous occupancy; an oxygen deficient atmosphere and or be subject to accumulation of contaminants, which may or may not be flammable.

To restrict the flow of pollutants / contaminants at the point where public water and customers water system meet, i.e. service connection of water meter, separated by a backflow preventer commensurate with the degree of hazard.

An impairment of the quality of the water, which creates an actual hazard to the public health through poisoning or through the spread of disease by sewage, industrial fluids, waste, etc. Also defined as high hazard.

The point on a vacuum breaker, which determines the minimum elevation above the flood rim of the fixture or receptacle served at, which the vacuum breaker may be installed. When a vacuum breaker does not bear a critical level marking, the bottom of the assembly / device shall constitute the critical level.

Any actual potential connection between a potable water supply and any source of non – potable substance, through which it is possible to introduce non – potable, used, unclean, contaminated water or other substance into the potable water supply.

Classification attached by discerning either high / health or low / non – health to an actual or potential cross connection.

A water line that been set apart or reserved for a specific use or purpose such as a fire suppression system or other process where nothing else supplied from that line.

An approved assembly consisting of two independently operating, internally loaded check valves, two resilient seated shut-off valves and appropriately located test cocks. Designed for backpressure, backsiphonage and low / non – health hazard only.

A cross connection that is subject to both backsiphonage and backpressure.

A facility or premise where two independent water supplies exist, one potable and the other non – potable. The purpose of the non – potable system is to reduce the cost of the potable water supply – i.e. secondary irrigation system.

A water line, which before or after entering a building provides for a water supply to more than one internal system – i.e. domestic use and fire suppression.

The highest level to, which water or other substance can stand within a tank or fixture (i.e. the overflow rim of the receiving vessel).

The appropriate state or provincial departments or districts of public health or, in some cases a local agency having jurisdiction.

An actual or potential threat of contamination of physical or toxic nature to a potable water supply that would be a danger to health..

A cross connection that is subjected to backsiphonage only.

Installation of a backflow protection at the point of use to provide isolation of a hazard within a consumer’s water system.

Authorized agent of the regulatory authority and or the water purveyor.

A hazard, which can cause aesthetic problems such as adverse effects on the odor, taste, and color of the potable water supply or have a detrimental effect but does not present a danger to health.

Any water, other liquid or other substance, which is not safe for human consumption, or is not a part of the public potable water supply as described by the health authority.

An impairment of the quality of the potable water to a degree, which does not create a hazard to the public health, but which does adversely and unreasonably affect the aesthetic qualities of such potable waters for domestic use.

Water, which is satisfactory for human consumption, culinary, and domestic purposes and meets the requirements of the health authority having jurisdiction.

Having the capacity to be; the possibility of.

The practice of protecting the public potable water supply by installing backflow prevention protection at or near the point where water enters the premise. This type of protection does not provide protection to personnel on the premise.

The normal force exerted by a liquid or gas, per unit of area.

An approved assembly consisting of a spring loaded check valve loaded to the closed position, an independently operating air inlet valve loaded to the open position and installed as a unit with and between two resilient seated shut-off valves and with properly loaded test cocks. Designed for backsiphonage only, both high / health and low / non – health protection.

An approved assembly consisting of two independently operating check valves, spring loaded to the closed position, separated by a spring-loaded differential relief valve loaded to the open position, and installed as a unit with and between two resilient seated shut-off valves and having four properly located test cocks. Designed for backpressure and backsiphonage and high / health and low / non – health protection.

Legislation that was enacted by the United States Congress in 1974 to ensure that the public is provided with safe drinking water. In 1996, the act was amended.

The pipping connection where the water purveyor loses jurisdiction and sanitary control of the water at its point of delivery to the consumer. In most cases, this is at the water meter.

The appropriate type or method of backflow protection at the service connection, commensurate with the degree of hazard downstream of the meter / connection.

An approved assembly containing an independently operating, internally loaded to the closed position a check valve and an independently operating, loaded to the open position air inlet, and installed as a unit with and between two resilient seated shut-off valves and with properly loaded test cock and a properly located bleed / vent valve. Designed for backsiphonage only, and both high / health and low / non – health protection.

The pressure increase due to the rise in temperature in water or other fluid in a closed system.

University of Southern California Foundation for Cross Connection Control and Hydraulic Research. An agency, which tests and approves backflow prevention assemblies by approved standards.

Any potable water, which is no longer in the purveyor’s distribution system. In most cases, the potable water has moved past (downstream of) the water meter and or property line.

An agency, municipal corporation, firm, company, subdivision of the state, mutual or cooperative association, institution, person or partnership or other entity that owns or operates a public potable water system or authorized agents of any of the above mentioned.

Any public potable water supply, which has been approved by the administrative authority having jurisdiction.

Any water supply on or available to the premises other than the approved water supply. This may include water from another purveyor’s water supply or any natural source such as a well, spring, river, etc.

Any water supply, which has not been approved by the administrative authority having jurisdiction.