A PVC check valve (or non-return valve) is a simple device that lets water flow in one direction but automatically stops it from flowing backward, protecting your equipment and preventing tanks from draining.
Swing Check Valve This valve has a flap inside that swings open to let water pass through with very little resistance. When the water stops, the flap swings shut.
PVC Spring Check Valve This valve uses a spring to hold a seal closed. Water pressure pushes the seal open to flow through. When the flow stops, the spring instantly snaps the seal shut.
