Everything You Need to Know About Your Sump Pump's Check Valve

By Shelley Frost

April 21, 2025

A sump pump is your best friend during rainy periods or anytime there's extra water around your home. You don't need to know every detail about how it works, but understanding certain key features of a sump pump makes it easier to keep it running properly. One important part is the sump pump check valve.

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What Is a Sump Pump Check Valve?

The sump pump check valve goes in the discharge pipe and is a one-way valve, meaning water can only flow through it in one direction. When the sump pump starts, the pressure of the water pushes the valve open so the water can run through it. The purpose of it is to keep water from going back into the sump pump pit once the pump stops running. By nature, the water wants to run back down the discharge pipe if the pump is no longer running.

There are two main types of check valves for sump pumps. One is the gravity or flapper style valve. Water pressure opens the valve, and gravity closes it once the pump stops running. The other common option is a spring-assisted check valve, also called a quiet or silent valve. The spring helps open and close the valve. It's quieter than a gravity valve.

Where Should a Check Valve Be Installed?

An ideal sump pump check valve location is in the discharge pipe, close to the pump itself. Locating it close to the pump means less water can run back into the pump. If you place it higher in the pipe, all the water below the valve will run back into the pump once it stops running.

A common sump pump check valve location is close to floor level. This offers access to the pipe for easier installation while keeping it close to the pump. You can install it lower in the pit, but it's not as easy to reach, which makes installation and servicing more difficult.

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Does Every Sump Pump Need a Check Valve?

Your sump pump will run without a check valve installed, but it's not a good idea to use it without one. If you don't have a properly working check valve installed, the water rushes back into the pit once the pump shuts off. Rising water levels inside the pit cause the pump to start running again to remove the water. This cycle repeats as the water remaining in the pipe continues to go back into the pit.

At the very least, this ongoing pumping uses more energy and raises your utility bills. The repeated on and off cycling makes the sump pump work harder than it should. In some cases, it could overheat. Between the increased usage and overheating, running the system without a sump pump check valve could significantly shorten the life of the appliance. Replacing it sooner costs you more money. You also run the risk of the pump failing when you really need it, which could cause your basement to flood.

How Do I Know If My Check Valve Is Faulty on My Sump Pump?

It's not always obvious when the sump pump check valve fails. Stand close to the sump pump while it's running. Once the cycle stops, watch for water going back into the sump pump pit. You could also have a faulty check valve if the sump pump seems to cycle continuously. Monitor how it runs and note if it seems to turn on right away after it shuts off.

A check valve failure can happen for multiple reasons. If you have the spring-style valve, the spring could become damaged or corroded. It could also become misaligned, preventing it from closing off the pipe completely. A buildup of debris can interfere with the valve working properly. The valve also can't work correctly if it's positioned too high in the pipe. A plumber can inspect your check valve to determine if that's the cause of your sump pump issues.

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