§ Backflow 101
When water reverses, the system fails.
Backflow is the unwanted reversal of water — or another substance — into a potable supply. It can happen quietly, and far from whoever opens the tap.
Supply pressure carries clean water one way. A working preventer keeps the non-potable source sealed off.
Pressure drops or reverses, and contaminated water travels back through an unprotected connection into the drinking-water main.
What creates the risk
01
Cross-connections
A physical link between potable water and an irrigation, fire, industrial, or process system.
02
Pressure loss
A main break or heavy demand drops supply pressure and siphons water backward.
03
Back-pressure
A pump, boiler, or tank pushes harder than the supply, forcing fluid into the main.
04
Failed assemblies
A missing, bypassed, or untested backflow preventer leaves the boundary open.