These PVC-U backflow preventers are non return valves with ring seal x spigot connections, the valves feature a handle for manual closing of the internal flap.

A backflow preventer can safeguard against contamination of water supplies and flooding caused by the backflow of waste water or effluent that occurs after a drop in pressure of mains supplies.

These non return valves operate automatically with no external power supply, the force of gravity in no-flow situations closes the internal flap preventing the backflow of water or effluent.

Backflow preventers are also known as backwater valves, drainage non-return valves and anti-flood valves.