This 3 inch lead free reduced pressure zone backflow preventer assembly is designed to prevent the reverse flow of fire protection substances and water of non-potable quality from being pumped or siphoned into the potable water supply due to backsiphonage and or backpressure. Its compact modular design facilitates easy maintenance with a single access cover for in-line repairs. It is ideal for protection in continuous pressure piping applications and at cross-connections identified as health hazards and from other contaminants found at the service line entrance. This assembly consists of a short lay length lightweight stainless steel body, resilient seated outside stem and yoke shutoff valves, test cocks, corrosive resistant stainless steel bottom mounted relief valve, and a patented cam-check assembly. This backflow assembly contains a flood sensor with SentryPlus Alert(R) technology to detect excessive water discharges from the relief valve. When activated through an add-on sensor connection kit, the flood sensor can send an alert to notify personnel about potential flooding. Add-on sensor connection kits are available for BMS and cellular communications.