Irrigation Saftey 101: What is a BACKFLOW preventer?

What is Backflow?

A backflow prevention device is used to protect water supplies from contamination or pollution. Many types of backflow prevention devices also have test cocks so that they can be tested or examined to ensure that they are functioning properly.

The Environmental Protection Agency (EPA) holds local water suppliers responsible for maintaining a certain amount of purity in potable water systems. Many states and/or local municipalities require annual testing of backflow prevention assemblies.

Backflow prevention protects the potable water system from minor, moderate, and severe hazards. There are over 10,000 reported cases of backflow contamination each year. Some cases can be fatal. Backflow devices are required by law where needed and must be installed in accordance with plumbing or building codes. A backflow assembly has test cocks and shut-off valves and must be tested each year, if relocated or repaired, and when installed.

ALL IRRIGATION SYSTEMS ARE CONSIDERED A HIGH HAZARD.

Common Irrigation Backflow Prevention Assemblies:



A Pressure Vacuum Breaker (PVB) is a type of backflow prevention device, used to keep non-potable (or contaminated) water from entering the water supply. A PVB is similar to an atmospheric vacuum breaker (AVB), except that the PVB contains a spring-loaded poppet. This makes it acceptable for applications that are high hazard or where valves are downstream. Pressure vacuum breakers must be protected from freezing when installed outdoors. PVBs usually have test cocks, to which specially-calibrated gauges are attached, in order to ensure that they are functioning properly.
PVBs are manufactured by Watts, Febco, Zurn and other manufacturers. Backflow prevention devices such as PVBs are regulated by the International Plumbing Code, but may also be required by government regulations.



A reduced pressure (RP) backflow prevention device is a device used to protect the potable water supply from contaminated water. An RP valve consists of an automatic pressure relief valve in between two check valves. The pressure relief valve opens to the atmosphere in the event of a reduction in the pressure differential between the first two chambers of the device.
The assembly is considered to provide redundant means of protection because: (1) check valves keep water flowing in one direction only, and; (2) the relief valve will operate in the event the supply pressure drops below atmospheric pressure.
Reduced pressure backflow preventers can be abbreviated RP, RPP (Reduced Pressure Principle) and RPZ (Reduced Pressure Zone). RP assemblies protect against backsiphonage and backpressure, and may be used where a potential hazard exists. RP valves can be found in commercial buildings, hospitals, and industrial applications.