Cross Connection Control

What is a Cross-Connection?

Cross-connections exist whenever the drinking water system is or could be connected to any non-potable source (plumbing fixture or equipment used in any plumbing system).  Pollutants or contaminants can enter the safe drinking water system through uncontrolled cross-connection when backflow occurs.

What is Backflow?

Backflow is the unwanted flow of non-potable substances back into the consumer’s plumbing system and/or public water system (i.e., drinking water).

There are two types of backflow conditions:

Backsiphonage - occurs when the supply pressure at the water connection point decreases below the pressure on the consumer's side.  This could be caused by a water main break, water system repairs or large fire demand.

Backpressure - occurs when the consumer-side pressure overcomes the normal supply pressure.  This could be caused by the operation of a boiler or a separate booster pump system connected to the consumer’s piping.

Where are Cross-Connections Found?

Cross-connections are found in all plumbing systems. It is important that each cross-connection be identified and evaluated as to the type of backflow protection required to protect the drinking water supply. Some plumbing fixtures have built-in backflow protection in the form of a physical air gap. However, most cross connections will need to be controlled through the installation of an approved mechanical backflow prevention device or assembly. Some common cross-connections found in plumbing and water systems include:

-Wash basins & service sinks

-Hose bibs

-Irrigation sprinkler systems

-Auxiliary water supplies

-Swimming pools/hot tubs

-Photo developing equipment

-Solar heat systems


-Fire sprinkler systems

-Water re-circulating systems