Existing Double Check Valve Assemblies (DCVAs) are installed above ground because in an underground installation the assembly is likely to become submerged in water during the winter months. If the assembly does get submerged underwater the manufacturer’s warranty is void. Also, above-ground installation of DCVAs is recommended by the Foundation for Cross-Connection Control and the Hydraulic Research University of Southern California, because a cross-connection between the test cocks and the water submerging the assembly is created.
Reduced Pressure Backflow Assemblies (RPBAs) are installed 12 inches above ground because this assembly dumps water when the assembly fails. Adequate drainage is needed to ensure discharging water does not back up and flood the assembly.