A DCA, or double check assembly, is the most common kind of backflow preventer for a sprinkler system. Double check assemblies are required by many state and local codes throughout the U.S. and are typically required to be retested on a regular basis. They are also sometimes called double check valves.
What is a backflow preventer?
A backflow prevention device is used to prevent drinkable water supplies from contamination due to backflow. Many systems that carry water or fluids have some sort of backflow preventer, including sprinkler systems, fire sprinklers, and home water systems. Typically they’re used to ensure that used water (such as the water that flows into your toilet tank) doesn’t accidentally flow backwards into the supply line where contanimants could taint the water supply.