Why do I need my "Backflow Prevention Assembly" tested annually?

Backflow Prevention Assemblies and Devices break or wear out, just like the parts of a car. By having your Backflow Prevention Assembly tested annually, you will help to ensure that the potable supply (drinking water) remains safe. Many cities have created this By-law to help insure the safety of drinking water.

Why have I never had to test my Backflow before?

When your backflow was installed it was tested prior to the plumbing inspection, but because of the volume of backflow preventers being installed and the large number of existing backflow preventers in various cities it is not easy for municipalities to keep you informed of when your backflow is due to be tested. However, due to increased awareness of the importance of protecting our water many cities are taking better steps to inform people when their annual test is due.

What is a cross-connection?

A cross-connection is any temporary or permanent connection between a potable water system and any source or system containing non-potable water or other substances. An example would be the connection between a potable water source and an irrigation system or a fire sprinkler system.

What is a Backflow preventer?

A backflow preventer is a mechanical way of preventing backflow. The mechanical parts provides a physical barrier from backflow of any water. The types of mechanical backflow preventers are the reduced-pressure principle assembly, the pressure vacuum breaker assembly, and the double check valve assembly.

What is an air gap?

The air gap is a vertical, physical separation between the end of a water supply outlet and the flood-level rim of a receiving vessel. This separation must be at least twice the diameter of the water supply outlet and never less than one inch. This basic way of backflow prevention eliminates a cross-connection and provides a barrier to backflow. An air gap is considered the maximum protection available against back pressure backflow or backsiphonage, but is not always practical and can be easily bypassed.

What is a reduced principle (RP) assembly?

An RP is a mechanical backflow preventer that consists of two independently acting, spring-loaded check valves with a hydraulically operating, mechanically independent, spring-loaded pressure differential relief valve between the check valves and below the first check valve. It includes shutoff valves at each end of the assembly and is equipped with test cocks. An RP is effective against back pressure and backsiphonage and may be used to isolate health or non-health hazards.

What is a pressure vacuum breaker (PVB) assembly?

A PVB assembly is a mechanical preventer that consists of an independently acting, spring-loaded check valve and an independently acting, spring-loaded, air inlet valve on the discharge side of the check valve. It includes shutoff valves at each end of the assembly and is equipped with test cocks. A PVB may be used to isolate non- health hazards, but is effective against back-siphonage only.

What is a double check valve assembly?

A DCVA is a mechanical Backflow preventer that consists of two independently acting, spring-loaded check valves. It includes shutoff valves at each end of the assembly and is equipped with test cocks. A DC is effective against back pressure and back-siphonage but should be used to isolate only non- health hazards.

What is backflow?

The undesirable reversal of flow in a potable (drinking) water distribution system, as a result of backsiphonage or backpressure.

What is backpressure?

Any condition that could create pressure in the non-potable piping system greater than in the potable (drinking) water system. Pressure caused by gravity due to elevation differences is an example.

What is back-siphonage?

A form of backflow due to a negative or sub-atmospheric pressure within a potable water system.