Backflow Testing Frequently Asked Questions

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 drinking water supplied to your home remains safe. Certified Testers can inspect, test, repair or replace all Backflow Prevention Assemblies and Devices.

What is a cross-connection?
A cross-connection is any temporary or permanent connection between a public water system or consumer's potable (i.e., drinking) water system and any source or system containing non-potable water or other substances. An example is the piping between a public water system or consumer's potable water system and an auxiliary water system, cooling system, or irrigation system.

What is a Backflow preventer?
A Backflow preventer is a means of mechanism to prevent Backflow. The basic means of preventing Backflow is an air gap, which either eliminated a cross-connection or provides a barrier to Backflow. The basic mechanism for preventing Backflow is a mechanical Backflow preventer, which provides a physical barrier to Backflow. The principal types of mechanical Backflow preventers are the reduced-pressure principle assembly the pressure vacuum breaker assembly, and the double check valve assembly. A secondary type of mechanical Backflow preventer is the residential dual check valve.

What is an air gap?
An 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. An air gap is considered the maximum protection available against back pressure Backflow or back siphonage, 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. An RP is effective against back pressure and back siphonage 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. 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 Backflow and back siphonage but should be used to isolate only non-health hazards.

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