How to Select the Right Pool Check Valve

Written by Michael Dean
May 28, 2024

swimming pool check valve

The pool check valve is a safety device that prevents water from flowing in the opposite direction it should. Pool valves can be automatic or manual and come in many different styles, depending on your needs. This article will discuss how to select the correct pool check valve for you and your situation. I’m here to walk you through everything you need to know about selecting the correct pool check valve to get your pool back up and running as soon as possible.

Main Takeaways

  • Check valves keep your pool water from flowing backward and can be used to help raised pool pumps, solar pool heaters, chlorinators, raised spas, spa blowers, ozonators, and spa overflow lines.
  • There are three types of check valves: spring check valves, swing check valves, and ball check valves.
  • To find the right replacement pool check valve, you should consider the number of valves, size, strength, opaqueness, connection, and location.

What is the Purpose of a Check Valve?

In short, pool check valves are a quick and easy way to keep water from flowing backward in pools, spas, or fountains.

They are helpful devices that prevent one-direction flow from occurring within most plumbing systems (water cannot go up through them). Check valves can be used to avoid gravity draining of water in the filter, pump, and pipes when a pool’s pump shuts off. They also keep raised spas, fountains, or solar heaters full of water when their own pumps shut off.

Specifically, you can use pool check valves for different purposes.

Raised Pool Pumps

Pool check valves keep water in the pool pump when it shuts off. They help inground pools have a fast prime by keeping the water inside the pump and filter while not allowing dirt from back-flowing into the pool. They’re usually only found on inground pools, not on above-ground pools, since they have equipment located below the pool water level.

Solar Pool Heaters

Check valves in solar pool heaters help keep the solar system from draining down once the pump turns off. You could also put another valve on the pipe that returns from the system. Placing one here will prevent the water from going back through the panels after the system is turned off.


Chlorinators can use check valves to keep chlorine from going back into the filters, heaters, or other equipment. This will help keep your equipment from getting damaged by too much chlorine.

Raised Spas

Remember, water wants to go down. When you put a fountain or spa at a higher level than the water in a pool, the water will drain when the pump turns off. Check valves keep water from going down (gravity draining) when you are not using these other water features.

Spa Blowers

For pools with spas, you might need a blower line that adds air to the spa jets. Many builders put the blower on top of a tall pipe so that water will not get into it and ruin it. Builders often put a check valve on it so that water does not get back in and destroy the blower.


Ozonators often use a ball check valve on the ozone feed pipe. These valves help keep gas flowing in a single direction while preventing water from flowing back into the ozone chamber.

Spa Overflow Lines

Pool spas use a bypass line to keep them clean and circulated. If the valves are closed, the overflow line sends water to the spa returns. In Spa Mode, a check valve is used on the overflow pipe to keep water from looping backward.

Different Types of Check Valves

The type of check valve you should use will depend on the purpose. There are three types of check valves for pool maintenance: spring check valves, swing check valves, and ball check valves.

Spring Check Valves

There are two types of spring check valves: a “normal” spring check valve and a spring flapper check valve.

A pool spring check valve is a clever device with an internal panel that travels against a spring to open and close the valve.

A spring flapper check valve has a flap on one of the valve ends. This flap pivots against a spring once the water starts coming out of the pump. The flap then releases downward, which closes any flow that would reverse course after turning the pump off.

Swing Check Valves

While spring check valves can be used in pools and spas, many people prefer to use swing check valves. There are two reasons for this:

  • Swing check valves don’t clog very easily when compared with the other styles of check valves.
  • The springs on a spring check valve can be prone to easily deteriorate, especially when they’re exposed to severe conditions.

Ball Check Valves

The final type of pool check valve is a ball check valve. While they’re not used as often as the other two types of valves, they are often used in chlorinators or ozonators—anywhere you might need a smaller-type check valve.

As indicated by their name, ball check valves use a small ball inside the valve, which makes a seal on just one side of the valve once the pump gets shut off. However, when the pump is on, the water flow pushes the ball to the other side of the valve, allowing the water to pass through the valve eventually.

How to Find the Right Replacement Pool Check Valve

There are a few things to consider when finding the correct pool check valve when maintaining your pool.


First, you want to consider how many valves are in your pool. If only one valve is on the swimming pool, then a single ball check valve might be ideal for replacing it.

If your pool has three valves (covers and skimmers), a triple-check valve would possibly work better. It has two balls that sit opposite each other, so water can flow through both directions if needed.


Another thing to consider when buying a replacement pool check valve is the size. Most pool check valves come in various sizes to fit standard pool pipes. Fortunately, some check valves can serve two different sizes, making it much easier to fit them where you need them. Also, look for the brand on your current check valve, which typically carries replacement valves. For example, Pentair is one of the market’s most popular pool valve brands.


Check valve strength is another thing to consider. For example, different spring valves come in various strengths. Most valves have springs that allow for reasonably light resistance; however, you’ll probably want to opt for something more substantial if you require more strength. This is especially true when you have increased pressure on backflow, which is often the case with solar panels installed on a roof.


Most check valves come in transparent or opaque. The good thing about clear valves is that you can see the mechanisms inside, which will help you see if the valve is clogged or stuck. Obviously, you won’t be able to do that with opaque check valves.


One of the most significant differences in pool check valves is between union and union connections. A union connection can easily remove a valve from the pipe without cutting it out. These types of valves might have threaded connections.

However, with non-union connections, the pipe is fitted into the valve and glued together for a more permanent solution. Typically, this might be a problem if you want to remove the check valve to clean it; however, with non-union valves, you can often access them through the top to be repaired quickly.


Finally, the location of your pool check valve can help you determine what kind to buy. Contrary to what some pool owners think, there is no best place to install a pool check valve. Instead, it would be best to simply put it where it’s needed.

For example, if you want to prevent water from reversing direction back up a line, you’d put the valve on a straight piece of pipe. Also, you wouldn’t put the valve in front of a pump because that could lead to priming issues.

As another example, you wouldn’t need to worry about where to put a pool check valve in relation to a diverter valve; you could put it either before or after the diverter valve because placement, in this case, wouldn’t do anything to affect the performance of the valve itself.

Need Some Maintenance Help?

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Check Valves Are Critical

Pool check valves are a necessary part of any pool maintenance. They are one of the most critical pieces in preventing expensive damage, and by keeping your valves maintained, you’ll be able to enjoy your pool even more.

With so many different types to choose from, though, it can be easy to get overwhelmed when selecting a pool check valve for your own situation; however, by following these tips, you should find that choosing an appropriate model is not as difficult as it might seem and something that you can easily do on your own. For more recommendations, head over to my pool pump ratings too.

Questions about check valves? Let me know; I am always happy to offer advice.

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