Cross-Connections

What is a Cross-Connection?

A physical connection between a public water system and either another supply of unknown or questionable quality, any source which may contain contaminating or polluting substances, or any source of water treated to a lesser degree in the treatment process.

Contamination - The presence of any foreign substance (organic, inorganic, radiological or biological) in water which tends to degrade its quality so as to constitute a health hazard or impair the usefulness of the water.

Pollution - Is an impairment of the quality of the water to a degree which does not create a hazard to the public health, but which does adversly and unreasonably affect the aesthetic quality of the potable water for domestic use.

What is backflow?

Backflow means an undesirable or unwanted reversal of flow of water into the distribution pipes of the potable supply caused by a differential in pressure.  There are two types of pressure conditions which cause backflow: backpressure and backsiphonage.

backpressure - occurs when the pressure in the downstream piping system is higher than the supply piping system pressure and can be caused by a pump, elevation, or boiler unit.

backsiphonage - occurs when there is a negative (below atmospheric) or reduced pressure in the supply piping caused by a main break, fire fighting, hydraulic flushing, pump failure, or high demand condition.

 

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