Where does a check valve go on a sump pump discharge line?

A check valve goes in the discharge line above the sump pump. The arrow on the valve should point away from the pump and toward the discharge outlet.

Can a check valve make a sump pump noisy?

Yes, a loose or poorly matched check valve can create tapping or banging sounds. A valve that closes too quickly may also contribute to water hammer in the discharge line.

How can you tell if a sump pump check valve has failed?

A failed check valve may let water flow back into the pit after pumping stops. The pump may then start again more often because returning water raises the pit level.

Glossary

What Is a Check Valve?

A check valve is a one-way plumbing device that lets water flow forward and blocks reverse flow. The valve opens when water moves in the intended direction. It closes when flow stops or pressure changes. This action helps protect pumps, pipes, and connected equipment from unwanted backflow.

Quick Facts About Check Valve

Key Takeaways About Check Valve

A check valve permits flow in one direction.
The valve helps stop reverse flow after a pump shuts off.
A check valve is not the same as a shutoff valve.

How Check Valve Works

Hands hold a brass pipe fitting with an arrow on a cluttered workbench, with tools and a laptop nearby

A check valve uses a movable part that responds to water pressure. Water flowing the correct way pushes the part open. Reverse pressure moves the part closed and seals the passage.

Related glossary terms: Backflow Preventer, Ball Valve, Shutoff Valve.

In a sump pump system, the valve sits in the discharge pipe. The pump sends water out through the pipe, and the valve allows that flow. After the pump stops, the valve blocks water from draining back into the pit. A sump pump and its discharge pipe need the valve installed in the correct direction.

Check valves come in several designs, including swing and spring-loaded types. The right design depends on pipe layout, flow conditions, and the equipment connected to the line.

A person holds a brass plumbing fitting and pliers while reading a screen about a check valve

Expert Note

When we work on sump pump systems, we check the valve's flow direction and fit within the discharge piping. We also watch for debris, sticking, or a poor seal that could let water return to the pit. Our team checks the pump and valve together so the system works as one unit.

Check Valve in Practice: A Real-World Example

A sump pump moves groundwater through its discharge pipe and out of the home. When the pump stops, the check valve closes so water in the pipe does not run back into the sump pit.