Reasons for Backflow Prevention

Two conditions create backflow. The first condition is backpressure; a greater pressure originating in the irrigation system can overcome the drinking water system supply pressure causing a reverse flow condition.

The second condition is backsiphonage; a suction created by the sudden loss of supply pressure, caused by water main breaks, and large demands such as fire fighting requirements.

Backpressure and backsiphonage can occur seperately or together. Different backflow preventers are designed to protect against one or both of these conditions.