Shop our selection of Backflow prevention, Backflow Valves in the Outdoors Department at The Home Depot..Shop our selection of Backflow Valves in the Outdoors Department at The Home Depot. Lead-Free Bronze Reduced-Pressure Backflow Preventer. Model# 34- .BrFIP x FIP Pressure Vacuum Breaker Backflow Preventer Check Valve. Model# 34- Apollo 1 in. Reduced Pressure Backflow Preventer, Lead Free, Black.. - Explaining Cross Connection and Backflow Prevention - A Shut off the water supply to the home by operating the main valve above the .