How to Fix Loud Sump Pump Thud Check Valve

How to Fix Loud Sump Pump Thud Check Valve: 7 Steps

Last Updated on May 16, 2023

A sump pump is a lifesaver during a heavy rainstorm, but the constant thudding noise it makes can be incredibly irritating. If you have a sump pump that is making a loud thudding noise, it is likely due to a problem with the check valve.

Sump pump check valves are designed to close when the pump shuts off so that water doesn’t flow back into the pit. But, sometimes, these valves can become worn or damaged, causing them to become noisy or stick open.

So here, we will discuss how to fix loud sump pump thud check valves. We will also provide some relevant answers to the questions on how to prevent your check valve from becoming noisy in the first place. So, let’s find out more.

How to Fix Loud Sump Pump Thud Check Valve: Identifying and Fixing

Identifying and fixing a loud sump pump thud check valve

As you know, sump pumps can sometimes make a loud thudding noise when they are turned on, which can be alarming for homeowners. The good news is that this problem is often relatively easy to fix. Follow the below-mentioned topics to find out more.

1. Check the Sump Pump Check Valve:

The check valve is a one-way valve that prevents water from returning to the sump pit after being pumped out. If the check valve is not working properly, it can cause a loud thudding noise each time the pump turns on. To test the check valve, simply turn off the pump’s power and then remove the discharge pipe.

Next, place your thumb over the hole of the discharge pipe and turn on the power to the pump. If your thumb is forced off of the opening, then the check valve is working properly. If not, then you will be required to replace it.

2. Clean the Inlet Screen:

Another possible cause of a loud thudding noise from your sump pump is a clogged inlet screen. The inlet screen is located at the bottom of the sump pit, and its purpose is to prevent foreign objects from entering the pump.

If the inlet screen becomes clogged, it can restrict the flow of water into the pump, causing it to run more often and make a deep thudding noise. In order to resolve this issue, it is necessary to clean the inlet screen.

3. Clean or Replace the Sump Pump:

A dirty or clogged sump pump can also cause a loud thudding noise. To clean the pump, simply remove it from the sump pit and disassemble it according to the manufacturer’s instructions.

Once you have cleaned all of the parts, reassemble the pump and put it back in the sump pit. If the pump is too dirty or clogged to be cleaned, it must be replaced.

4. Adjust or Replace the Float Switch:

Adjust or Replace the Float Switch

The float switch is a device that turns the sump pump on and off as needed. If the float switch doesn’t work right, the pump will thud every time it turns on or off. To test the float switch, turn the pump off and then take out the float switch from the sump pit.

Next, place your hand over the opening of the float switch and turn on the power to see if it activates correctly when covered and deactivates when uncovered again. If not, you will need to adjust or replace it according to the manufacturer’s instructions.

5. Inspect for Leaks:

An air leak in the discharge pipe can also cause a loud thudding coming from your sump pump. The discharge pipe is what carries water away from the sump pit after it has been pumped out.

If there is any leakage along the discharge pipe, it can cause water to back up into the sump pit, which will make the pump cycle on and off more frequently and make a deep thudding noise.

6. Replace the Impeller:

The impeller is a device that helps to move water through the pump. If the impeller is damaged, it can cause the pump to make a harsh thudding noise. To fix this problem, you will have to replace the impeller.

You can find replacement impellers at most hardware stores. Simply remove the old impeller and install the new one.

7. Call a Plumber:

If you have tried cleaning the pump and checking the impeller, but the noise persists, you may need to call a plumber for assistance. They will be able to properly diagnose the problem and make any necessary repairs.

Why Does My Sump Pump Thud?

There are several reasons why a sump pump might thud. One possibility is that the float switch is not working properly and is allowing the pump to run dry. This can damage the pump and cause it to make noise.
Another possibility is that something is obstructing the flow of water through the pump, causing it to work harder than usual and make noise. Also, it is possible that the bearings in the pump are failing and need to be replaced.

Why Does My Sump Pump Thump

How Can You Tell If a Sump Pump Check Valve is Bad?

If your sump pump check valve is not working properly, there are a few tell-tale signs to watch out for. To begin with, you may notice that your sump pump is cycling more frequently than usual.
Also, you may see water starting to accumulate in the sump pit, even when there has been no recent rainfall. Then, if you can hear water running or gurgling even when the sump pump is not in use, this is another indication that the check valve is not functioning properly.
If you suspect that your sump pump check valve is bad, it is important to have it replaced as soon as possible to avoid expensive damage to your home.

Why Does My Sump Pump Check Valve Bounce?

There are several potential causes of a bouncing Check Valve. One common cause is an improperly installed Check Valve. If the Check Valve is not installed correctly, it can allow water to seep back into the sump pit.
Another potential cause of a bouncing Check Valve is a clogged or frozen discharge pipe. If the discharge pipe is clogged or frozen, water will be unable to flow freely through it. This can cause the sump pit to fill with water, causing the check valve to bounce.
Likewise, a bouncing Check Valve can also be caused by a faulty Pump. If the Pump is not able to create enough pressure to open the Check Valve, it will bounce. A qualified technician will be able to diagnose and repair any of these issues.

How Close to the Sump Pump Should The Check Valve Be?

In most cases, the check valve should be installed as close to the sump pump as possible. This will help to ensure that the pump can expel water quickly and efficiently. Also, it is important to make sure that the check valve is installed in a way that prevents it from becoming clogged with particles.
If the check valve becomes clogged, it can reduce the effectiveness of the sump pump, causing frequent cycling, and making a loud thudding sound. Due to this, it is important to carefully consider the location of the check valve when installing a sump pump system.

Is it Necessary to Fix Loud Sump Pump Check Valves?

If you’re considering whether or not to replace a damaged or noisy check valve, there are a few things to keep in mind. As a start, consider the age of your sump pump. If it’s more than 10 years old, it’s probably time for a replacement anyway.
Also, think about how often the pump is running. If it’s only occasionally, you may be able to get by with a repair. But, if the pump is frequently running, it’s probably best to replace the check valve. To finish, consider the cost of replacement parts and labor.
In most cases, it’s cheaper to replace the entire sump pump than to try to repair a damaged or noisy check valve. With all of these factors in mind, you can make an intelligent choice about whether or not to fix your loud sump pump check valve.


A sump pump check valve is an important component of any sump pump system, as it helps to prevent water from flowing back into the sump pit. While a faulty check valve won’t necessarily cause your sump pump to fail, it can shorten its lifespan and lead to expensive repairs.

That’s why we have extensively covered different aspects of loud sump pump check valve thuds. Hopefully, after following the instructions, you now have a sump pump with less or minimal noise. Thanks for reading.

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