Cross-Connection, Backflow Prevention, Back Siphonage

Item 36 Cross-Connection, Backflow Prevention, Back Siphonage 3 points

Cross-connection occurs when a potable water system is connected to a non-potable water system. Cross-connections may occur in many different ways. An example of a cross-connection is when a hose is attached to a faucet and then placed into a sink filled with water. This situation may lead to back siphonage.

Back siphonage can occur during times of extraordinary demand where a negative pressure is created in portions of the water system. This negative pressure would allow the contents of the sink to be sucked through the hose and contaminate the potable water supply.

To prevent back siphonage, a backflow prevention device or an air gap must be provided at critical areas.

To prevent sewage from backing up into food preparation sinks, ware washing sinks, ice bins, refrigerators, and ware washing machines, a physical air gap must be provided in the waste line. The physical air gap does not allow sewage to back up into fixtures should a sewage backup occur.