Backflow prevention
A device or design feature that stops contaminated water from being drawn backwards into the potable water supply.
What is Backflow prevention?
Potable water systems are meant to flow one way. If supply pressure drops — a water main break, heavy draw from a hydrant — water can siphon backwards and pull contaminants into the drinking supply. Backflow prevention takes several forms: an air gap between a faucet outlet and a fixture rim, a vacuum breaker on a hose bib or irrigation system, or a dedicated backflow preventer assembly on a boiler feed or lawn system. In a home inspection the usual observations are missing hose bib vacuum breakers, a handheld shower head that can reach below the tub rim, or a utility sink faucet submerged by a hose. These are inexpensive to correct and are reported as health-related items.