Informational Guide

What Is A Sump Pump Check Valve?

by Ian Haynes

sump pump helps protect your home by removing water from your basement or crawl space. The sump pump operation is fairly simple, and when enough water gathers, it should automatically kick in to pump water into your drains and out of your home.  

The check valve on the pump is one of the most important components, and in this guide, we'll help explain what a sump pump check valve is and everything you need to know about maintaining it.  

How It Works 

Your sump pump is triggered when there's too much water in your sump basin. The pump forces the water to flow into your drain by pushing it through a series of pipes. Most of the time, your sump pump is in the lowest part of your home, and your discharge pump will go up vertically until it can exit your home. Your check valve only allows water to travel in one direction through your discharge pipe and prevents it from falling back down into the sump basin. Without a check valve, the sump pump could end up running continuously and overheating. 

Most sump pump check valves are made from metal or plastic, and there are two common types:  

  • Spring Loaded Clear Check Valve 
    Spring loaded check valves allow water to flow through them one way and then use a spring to close the valve as quickly as possible. This helps prevent any water from slipping back down into your sump pump, and the spring action makes this type of check valve well suited for larger amounts of water. You'll often find spring loaded check valves on mains-powered sump pumps. Spring loaded check valves operate more quietly, and there's no loud noise as the valve closes.   Clear check valves are made from clear plastic and offer the added benefit of seeing directly into the valve. This allows you to check for any blockages, debris, or damage without having to remove the whole thing. A useful feature if you’re going to be using the sump pump frequently.  
  • Gravity Check Valve 
    Gravity check valves are cheaper and a bit simpler. They have a flap that opens one way as water is pumped through them but naturally closes due to gravity once it has all passed through. This type of valve takes very little force to work and is best suited for battery powered sump pumps. You'll find this style of check valve in any local hardware store.  

Why It’s Important 

So why do sump pump check valves matter? There are 4 key reasons you need to have one connected to your pump system: 

  • Pumping Efficiency 
    Your check valve prevents water from going back into your sump pump system. This helps improve the overall efficiency of the operation and prevents your pump from having to work more than once to remove the water.  
  • Pump Protection 
    Without a check valve, your pump is likely to run too frequently because it has to remove water continuously. This short cycling is bad for the machine because it causes overheating. This overheating will eventually damage your electric motor and prevent the pump from running. A check valve is an inexpensive way to protect your pump.  
  • Extends Sump Pump Life 
    By preventing short-cycling, you don't just protect your sump pump, but you extend the lifespan. This helps improve the pump's longevity, and it should last 10-15 years.  
  • More Location Choices 
    Your sump pump should be in the lowest part of your home for maximum efficiency. This is where it can gather and drain the most water and protect your home. Without a check valve, your sump pump won't be able to effectively pump water directly upwards, so you'll be limited in where you can place it. By installing a check valve, you can put your sump pump system in the lowest location, which will be more effective.  

Where Is The Sump Pump Check Valve Located? 

The location of your check valve matters just as much as the type of check valve. If it’s not installed in the right place, then it could be ineffective and damage your sump pump system.  

The check valve is connected to the discharge pipe, which runs through the sump basin lid and eventually connects to the drain. It's important to keep your sump pump check valve as low as possible as this reduces the amount of water that can flow back downwards into the pump after it's finished running. The higher up the check valve is, the more water will flow back downwards into the basin when it shuts off. 

It is sometimes installed within the sump pump basin itself, but this makes it more difficult to be checked and replaced. For easier maintenance and upkeep, it's usually easier to have it fitted just outside the pump basin.  

Sump Pump Check Valve Installation (Connection Types Explained) 

There are several different types of sump pump check valves, each with different connections to integrate them into your discharge pipes. Some are easier to install than others, but threaded are generally the simplest and most common. Here's a quick breakdown of the 5 different types: 


Threaded connections are really simple and usually twist into place. There are two varieties, male or female threads. Male threads are on the outside of the pipe, and female threads are on the inside. You should check your pipes, and if they have threading, you’ll need a matching threaded check valve. These are cheap and easy to install, but you should use a plumbers wrench to make sure it’s all connected tightly.  


Barbed check valve connections need to be used in conjunction with a hose clamp to hold it in place. You attach it to your pipes by simply sliding the hose clamp onto the discharge tube and then sliding the barbed connection into the pipe. The design of the connection should mean it should hold in place on its own. If you’re using a corrugated drain hose, then this is the type of check valve you need. Barbed connections come in all sizes, so make sure you've got the right size so it holds in place.  


The slip or spigot connection should be used with PVC discharge pipes. The slip is the female, wider end of the connection, and the spigot is the narrower end. You'll need to slide the PVC pipe into a socket that connects into the slip or spigot, which in turn connects into the check valve. These are also pretty simple to install yourself, and they will hold securely.  

Flexible Rubber Coupling (Rubber Boot) 

Your flexible rubber coupling comes all in one and removes the need to buy multiple parts. The coupling just slides over the discharge pipe and has tightening clamps to help hold it securely in place. It’s a cheap option but won’t work on very narrow pipes because it won’t be able to seal tight enough.  


Compression connections are simple and easy to install and remove but a little more expensive. There is a sleeve that slides over the pipe and connects into the check valve and then nuts on either end to tighten into place. You'll probably be able to do this by hand, but a plumbers' wrench may be useful to ensure it's tight. This is the most durable connection and should last longer than the others on the list.  

isolating valve

How often should a sump pump check valve need to be replaced?  

Your sump pump should last over 10 years, but the check valve itself will probably only last 5-7 years before it needs to be replaced. You should inspect the check valve every year or so to make sure it's running properly, and it's helpful to have a simple connection so you can remove it if needed.  

How To Tell If Sump Pump Check Valve Is Bad  

Your check valve will see a lot of use, and it's essential to maintain it properly, or your whole sump pump system won't work correctly. Here are a few tell-tale signs that your check valve is bad and needs some attention: 

It Is Taking Longer Than Usual To Discharge Water 

If you notice your sump pump is taking longer to get rid of the same volume of water, then it could be an issue with the check valve. If it's not working properly, then the water will be flowing back into the basin as quickly as it's being pumped out. You should inspect the check valve for any visible blockages and remove it if needed. If there’s still an issue, then you should look to replace the valve.  

Leaks Or Moisture On Seals, Connection & Valve 

If you notice any moisture gathering around the major seals and connections, there's probably an issue with the check valve. Leaks indicate that water isn't draining properly from your system and could mean that your check valve isn't stopping water from flowing back down into the system. Use a plumbers' wrench to tighten all your connections and reseal if necessary. If you still notice leaking, your check valve could have gone bad.  

Fill The Sump Pit With Water To Check Drainage 

If you have a suspicion that the check valve is bad, then you can test it easily enough. First, fill your sump basin about halfway with water and see if the water drains as the pump runs. If your pump is running properly and the water isn’t draining, you’ll need to investigate issues with your check valve.  

Look Out for Water Running Back Down During Rain 

Another clear sign that your check valve is bad is that water flows back into the basin. When it's raining and your sump pump is running, you can check for water visibly running back down into the basin out of the discharge pipe. This means there's definitely an issue with your check valve, and it may need to be replaced.  

Short Cycling 

If you notice your sump pump running, shutting off, then quickly running again, it could mean there's an issue with your check valve. As water is pumped out, it's falling back down and triggers the pump to run again. Short cycling can be caused by several factors, but it's worth looking at your check valve first to see if there’s a problem. 

People Also Ask (FAQs)

Is a check valve necessary on a sump pump? 

Yes, without a check valve, your sump pump won't effectively get rid of water from your home.  

How can I tell if the sump pump check valve is working correctly? 

If your pump is running properly and the water is draining, then it means your check valve is doing what it should be.  

How close should the check valve be to the sump pump?  

Your check valve should be as close to the sump pump as possible so that it limits how much water can drain back into your basin once the pump stops running. Some check valves are located inside the sump basin beneath the lid, but it’s easier to maintain your check valve if it’s just outside the basin.  

What happens when the sump pump check valve fails? 

If your check valve fails, the gravity will cause some drain water to flow straight back into your sump pump system. This can lead to flooding, and your sump pump can become damaged because it's overworking.  

Where can I buy a silent check valve for a sump pump?   

Some check valves can be pretty loud, and there can be a slamming noise once your pump stops running. This is caused by the closing of the valve, which prevents water from flowing back down your discharge pipe. Spring-loaded check valves close much more quietly, and there are some good silent models available from Menards and Home Depot. 


Sump pumps have an important role to play in protecting your home from excess water, especially during rainy periods. Your check valve helps the sump pump system run properly and keep water flowing in one direction, out of your home. Without a functional check valve, your sump pump will be useless and can even become damaged. Hopefully, this article has given you some useful information and helped explain why sump pumps are essential.  

Ian Haynes is an expert writer who has successfully deployed over 500 plumbing pages and other related content. He has an excellent understanding of home plumbing issues and translates his experiences via Plumbing Lab so readers can have a better understanding of common household problems. Outside of his work, Ian likes exploring Brooklyn with his Labrador.