Backflow Preventers Explained: When You Need One

A backflow preventer is a plumbing device designed to stop backflow—the unwanted reversal of water flow that can pull contaminants into a building’s drinking-water lines. Instead of water moving normally from the supply into your home or facility, pressure changes can force water to flow in the opposite direction, creating a potential health risk.

Backflow can occur when there’s a drop in water pressure on the public side (for example, during a main break or heavy demand). If your plumbing has certain connections or risk sources, contaminants may be drawn backward through the system.