If you are using PVC pipe in a one-way water flow situation, it is important to know what a PVC check valve is. A PVC check valve, also known as a non-return valve, is a special valve made of PVC and installed on a PVC water pipe line that only allows the flow of water in one direction through the valve. The two most common ways to achieve this are either with a ball valve or a swing valve.
Ball PVC Check Valves
A ball type PVC check valve operates by restricting the flow of water in one direction using a floating ball that will block the valve. When water flows the desired direction the ball is pushed away from the valve opening.
Swing Check Valves
A swing type PVC check valve uses a hinged flap or flaps that swing open when water pressure comes from the desired direction and allow water to flow through. Adversely the swinging flap is pushed closed when water pressure comes from the non desired direction forcing the swing door closed inside the valve and restricting water movement.