The simplest method of preventing backflow is to create an air gap, which is an open vertical space between any piping system-connected device and any location where contaminated water can collect. The installation of a device called a backflow preventer may be required when there is not enough space to create an air gap.
There are several types of backflow preventers, including:
Backflow is a common fire protection system issue. Backflow refers to the reversal of the flow of non-potable water in the piping of a sprinkler
system that can contaminate a drinking water supply.
There are two primary causes of backflow: back pressure — which occurs when the pressure in downstream piping rises above the supply
pressure of the piping system — and back siphonage, which is the result of the supply pressure dropping below the water system pressure.