Modern technology has provided us with new tools to prevent backflow from non-potable sources into our public water systems. They are called backflow prevention assemblies; reduced pressure (RP) or double check valve (DC)-type. Unlike the older accepted, non-testable hardware for preventing backflow such as swing check valves, dual check valves and atmospheric vacuum breakers (which still have their applications), the RP and DC-type backflow prevention assemblies are testable to assure they are in proper working order. Placed at the site of the cross-connection they can protect the plumbing system from contamination. Placed just downstream of a water meter to an establishment, they can protect the public water system from any contamination that may occur within the entire establishment’s plumbing system.