The selection of a backflow prevention device is based on several factors. However, backflow prevention devices are required if there exists an actual or potential hazard for cross-connection. These devices must be American Water Works Association (AWWA) approved.
Some of these hazards include:
Fire sprinkler systems
Well, lake, and reclaimed water sources
Two commonly required backflow prevention devices are the Double Check Valve Assembly (DC) and the Reduced Pressure Zone Assembly (RP). Both of these protect your public utility drinking water system from backflow created by back siphonage and back pressure.
The RP backflow prevention device is used for potential health hazards such as sewage, medical fluids, and chemicals.
The double check or DC is used to protect the utility system from non-health hazards such as odor, color, and taste. These include well water, swimming pool water, or nontoxic industrial fluids such as dye or food products.
The District recommends the assistance of a licensed plumber certified by AWWA for backflow if you have any questions.