Backflow Prevention

Backflow is the reverse flow of water or other substances through a cross-connection pipe which flows back into the treated water distribution system. There are two types of backflow: Backpressure and Back-Siphonage:

a) Backpressure: Backflow that occurs when the pressure in an unprotected downstream piping system exceeds the pressure in the supply piping.  

b) Back-Siphonage: Resulting from negative pressure (vacuum or partial vacuum) in the water distribution system.

State regulations require All commercial and industrial customers to have a backflow prevention assembly on all services to contain any potential hazard from reaching the water main if a backflow event occurs. As a commercial or industrial customer, you are required to install, maintain, and test the appropriate State-Approved Backflow Prevention Assembly. Your backflow should be tested by a registered Certified Backflow Tester and all results should be sent to the Program Coordinator by the tester.

All backflow prevention assemblies must be both State approved and provide the appropriate protection for the degree of hazard present. They must be able to be tested for operational purposes and monitoring.

The type of backflow device necessary depends on the degree of hazard present at your location; taking into account how water is used at your location and any conditions that might allow contaminants to enter the main water infrastructure system. All backflow assemblies must be testable to meet criteria for installation on waterlines. The three (3) main types of testable backflow prevention assemblies are:

The PWMD Utility Department recommends that you have someone who is qualified for installation and certified for testing backflow devices.