To look at, a check valve seems to be an incredibly basic and simple valve but they are very important to your swimming pool, and your home. That’s right, they are found just about anywhere there is water and prevent it from damaging your system. Essentially, they make sure water is flowing in one direction but their importance should not be underestimated.

There are different types of check valve and they serve unique purposes. When it comes to swimming pools, it is important to know what they are, and the purpose they serve. To offer a bit of clarity, and help you know your pool system better, we have compiled the following to help.

What Is A Check Valve Used For?

When a pump turns off, you don’t want water flowing in the wrong direction. This is bad news for your whole system. A check valve keeps water flowing the way it should and prevents water from naturally traveling the wrong way, even when gravity would normally push it. This protects your pump, piping, and even the filter itself from damage.

They can also be used to make sure the likes of fountains are constantly filled with water so they are important for different reasons.

What Else Is A Check Valve Used For?

When it comes to swimming pools, there are pipes everywhere, and they are useful in different ways. For example, a chlorination device will keep a level of chlorine flowing but a check valve is used to make sure it does not interact with the rest of your pool equipment. You will find a check valve before this chlorination device to make sure it does not flow backward into the main system.

Types of Check Valves

There are two common types for swimmng pools and are only subtle differences.

Spring Check Valve

As the name suggests, this check value uses a spring to open and close the valve, pushing the panel the correct way to prevent water from traveling the wrong way. When the water pressure is reduced, it pushes the panel to seal the valve internally, preventing reverse flow.

Spring Flapper Check Valve

Again, another spring method but this one has the flap at one end that opens when water is flowing and when the pump is off, it blocks water by shutting.

Raised Pool Pumps

When it comes to swimming pools this is where you are most likely to find a check valve. Because the motor comes on intermittently, the check valve protects the system when it switches off. This allows the pump to hold water and stops it from flowing the wrong way.

Why Choose A Clear Check Valve?

To see inside the main mechanism, it is important to use a clear check valve. Some are opaque and even darker shades but a clear one allows you to see if there are any blockages that are effecting performance. There could be something keeping the valve open when it is not supposed to be and a clear product will allow you to get a good look.

This speeds up the process of finding faults in your pool system.

Removing Debris From A Check Valve

When removing any type of check valve, always turn the pump off first.

Removing Spring Flapper Check Valve Debris

You might think your old check valve needs replacing because the reverse water flow is getting through but some times, a simple clean up is all it requires. Usually, they are sealed by 8 nuts or a cover nut. The latter is far more convenient when it comes to inspecting the device as it is easier to lift off to get to the cover and subsequently inside the valve. This is where you will find any debris that has found its way inside and can remove it.

When you remove the cover, the flapper will come out too if this is the type of valve you have. Once you have cleared the debris you can reattach the cover and seal before securing it to back where it belongs.

Removing Spring Check Valve Debris

This is where it is better to have a clear check valve as you will be able to see the debris before you start to take it apart. To do so, unscrew the collars either side of the valve and it will fall when loose enough. Be sure to secure a towel underneath or have a hand ready to catch it and avoid any damage. From here you can remove any clutter or debris and whilst the check valve is removed, it is an opportunity for you to check inside the collars to see if anything is sticking out.

Make sure the O-rings around the collars are in good working condition before reattaching the spring check valve, taking care to ensure it is pointing the right way.

Can I Repair A Check Valve?

When it comes to the spring mechanism inside a check valve, it is only possible to repair a flapper check valve. A faulty or broken spring check valve will more than likely need replacing if the spring is damaged because it is not possible to open it to carry out the repairs.

On the other hand, a spring flapper check valve can be accessed via the top for repairs. Fortunately, swimming pool check valves are reasonably priced so if you do find yourself needing a new one, it shouldn’t set you back a lot.

How To Install A Check Valve

Installing A Spring Check Valve

Before installing a new check valve, always turn off the pump first.

This is where some people unnecessarily call in an expert who charges them for their time. Installing a new spring check valve is incredibly easy, it’s a matter of unscrewing the faulty valve from the collar and screwing the new one on. It is advisable to check the condition of the O-rings so they are sealing the piping correctly and when you have fitted the new valve, be sure to check it is facing the correct way. Usually, an arrow will indicate the direction of the flow.

When it is in place, check that there are no leaks when water is flowing.

Installing A Flapper Spring Check Valve

Fortunately, more often than not, you can repair a flapper spring check valve rather than replace it completely. This is good because replacing it can be a little more challenging than a regular spring check valve.

Sometimes they are attached without unions which will require you to cut out the valve. Give yourself a bit of room, half an inch to an inch eitherside should suffice.

Then you will need to measure the gap. The next stage will require a small bit of handy work. Cut a small piece of pipe and secure it to the current piping with a connector to seal it in place, with the flapper spring check valve in the middle.

Make sure the flow arrow is pointing the right way before gluing everything in place. Wait a couple of hours for the glue to dry, or consult the brand’s instructions before turning the water on. When the adequate time has passed, turn the pump on and check for leaks.

Alternatively, a check valve that comes with unions can make this process a lot simpler, and take away the strain from future replacements.


A check valve is something that many people never see, but take for granted. It has an important role to play in ensuring your pool is fully operational. Repairing and installing them can be simple, just like the device itself.