Backflow is the unwanted reverse flow of water or other substances. When backflow happens in a situation without a backflow prevention assembly, the water at the point of use can be either siphoned or forced back into the public distribution system, potentially polluting or contaminating it.
A cross-connection is the point at which it is possible for a non-potable substance to come in contact with the potable drinking water system. To prevent backflow from occurring, a backflow prevention assembly must be installed at the cross-connection or at the meter to isolate the private water system from the public water system.
Per the California Code of Regulations, backflow prevention assemblies must be tested annually.
Backflow certification form