Updated: Dec 7, 2018
Backflow is the unwanted reverse flow of water or other substances into a potable water system. Backflow preventers are installed to prevent the potable water from being contaminated if a backflow incident occurs. This can happen for two hydraulic reasons: backpressure and/or backsiphonage. This need to assure that water in an irrigation system stays separated from the potable water is critical. The water in an irrigation system comes in contact with pesticides, fertilizers and other residues and is therefore unfit for human consumption.
For this reason, all plumbing codes recognize irrigation systems as a hazard which requires a separation from the potable drinking water. This separation involves the use of backflow prevention assemblies. These assemblies are installed to ensure that the potable water is not contaminated. These assemblies are required to be periodically tested and maintained by personnel with special certifications to ensure that the assemblies continue to provide needed protection. These assemblies also have very specific installation criteria to ensure continuous functioning. This installation criteria requires that the assemblies must be installed above grade and usually outside. During the winter months, most irrigation systems and their backflow assemblies are shut off and the sprinkler system is drained of water or winterized. In some installations, the water must remain on during the winter months. This leads to the need to place the backflow assemblies in an enclosure to protect the assembly from the adverse effects of the environment.