Backflow is the movement of used or non-potable water back into a clean or potable water system rather than its normal flow. In water systems, water is intended to flow in a certain direction, usually from the source in the street to the fixture or appliance in your building, the reverse flow of non-potable water into a potable water source can be dangerous. Backflow is caused by the increase of pressure on the building side or at the “point of use” which results in the flow of water back toward the source. Backflow is avoided if you have no cross connections between potable and non potable water systems.
Simply put if water that has entered your irrigation system, toilet, or any other contaminated area gets siphoned back into the supply line.
Why is back-flow prevention important?
Plumbing problems like a water main bursts, pipes freeze or an unexpectedly high demand on the water system can also create a suction effect, possibly drawing contaminated water into the drinking water system. For this reason, back-flow or cross-connection can be a serious health risk. It allows contaminants such as fertilizers, pesticides or animal residues to flow back into potable water supply system. Connections between the water supply and a source of contamination are called cross-connections.