Backflow Preventers are mechanical plumbing devices installed to prevent water from flowing backward in a system. A back flow is dangerous because it can contaminate and make drinking water unusable and unsafe.
Sanitary sewer valves (check valves or backwater valves) are also referred to as "Backflow Preventers".
These Backflow Preventers need to be tested periodically. Fouling, wear and fatigue sometimes happens with the internal seals, springs and moving parts. It is important that the Backflow Preventers are functioning correctly. It is not sufficient to check visually. Mechanical Backflow Preventers need to be tested with properly calibrated gauge equipment.
Backflow Cross-Connection is any connection between the public water supply and a source of contamination or pollution. Some common Cross-Connections are:
Backflow through Cross-Connections can occur when using a garden hose to apply insecticide to your lawn, leaving your hose in a puddle after getting your lawn treated with insecticide, flushing out radiator fluid from your vehicle, or simply submerging the hose end into a pool to fill.
The possibility of Backflow into your clean drinking water can occur when the pump from an untreated supply, such as a private well, are connected to the drinkable water supply. Water which serves your home and the public system could be compromised by the untreated water pumped into your drinkable water supply.
Ensure that your garden hose doesn't become immersed in or near an undrinkable substance. This solution doesn't cost you money, but not everyone can always be this careful and it is not very reliable.
These inexpensive devices are designed to allow water to flow in only one direction. Before using a hose-end sprayer, you should first install a hose bibb vacuum breaker at the faucet. This method is only good for helping with grade hose backflow issues, not sprinkler systems.