How To Maintain and Repair Your Multiport Valve

Written by Michael Dean
February 7, 2024

pool multiport valve and maintenance checklist

Maintaining your pool is crucial to ensure your water stays safe and clean all season long—especially when taking care of your multiport valve! If your multiport valve is damaged or leaking, you should fix it as soon as possible! But how do you repair it? And how can you prevent it from breaking in the first place?

In this article, I will answer all of these questions and walk you through how to fix various things that can go wrong with your multiport valve.


Main Takeaways

  • The multiport valve contains several valve ports that allow your pool’s water to move around so you can filter, circulate, and backwash it as needed.
  • If your multiport valve is leaking at the handle, you will likely have to replace the O-ring.
  • If the spider gasket is broken, you’ll need to remove and replace it. The spider gasket directs the flow of water to your multiport valve.

What to Do When Your Multiport Valve Is Leaking Around the Handle

You can easily fix this issue as long as your valve rotor is not damaged or cracked! If that is the case, you should replace the valve rotor or try using aqua fix-it. However, if your multiport valve is leaking around the handle and your valve rotor isn’t broken, you’ll need to check the O-rings. Likely, there is something stuck under the O-rings of your valve rotor, or they may have gotten moved somehow.

To stop the leaking, clean the O-rings; apply silicone lubricant when you’re done to prevent them from cracking or drying out,, and adjust them back onto your valve rotor. If your O-rings are damaged or too dry, you can easily replace them for a few dollars by visiting your local pool store or hardware store.

What to Do When Your Multiport Valve Is Leaking Around the Cover

You should always check the pressure levels of your multiport valve if it is leaking around the cover.

If the pressure levels are above average, check your return lines for blockages and backwash your filter. If the pressure levels are low or average, then check your assembly O-ring. You can do this by unscrewing the whole multiport assembly from the part attached to your sand filter.

Chances are, your O-ring is probably dried out or damaged and will need to be fixed or replaced. Once you have disconnected your multiport assembly and inspected your O-ring, you will have to do one of two things:

  1. If the O-ring is broken or cracked, you must replace it.
  2. However, if the O-ring is intact, remove it and clean the surface area it sits on to ensure there is no debris in the way. Then, wash the O-ring well and apply some silicone lubricant before reattaching it.

What to Do When the Body of the Multiport Valve Is Leaking

There are quite a few reasons that may cause your multiport valve body to leak, but, for the most part, they can all be easily fixed. Of course, make sure you thoroughly inspect your multiport valve body to determine if it is an internal or external issue. It is also important to note that three ports make up the multiport valve body: the waste, the return, and the pump.

The return port may leak because the hot water from the pool heater can heat and shrink the PVC connector. Or the valve adaptor may cause leaking near the pipes if it is over-tightened. For the most part, all you will have to replace is the pipes and PVC fittings to stop these leaks.

It is cheaper to replace the valve body than to replace the entire valve, and your local hardware store should have whatever pieces you need to help stop the body of your multiport valve from leaking.

What to Do When Your Multiport Valve Is Leaking from the Waste Port

When you backwash the filter of your multiport valve, you will see water come out of the waste port. However, you should not continue to see water come out of the waste port after you are done backwashing. If that is the case, there may be some debris stuck between the spider gasket and the rotor of your multiport valve. If so, you will need to flush out your multiport valve so the rotor can be repositioned onto the spider gasket.

The Step-by-Step Process

To fix this issue, follow these steps:

  1. Shut the pump off and push the handle completely down, then turn the multiport valve slightly to the right and the left, and back into the filter position.
  2. Check the pump again by turning it back on.
  3. If your multiport valve is still leaking from the waste port, you should turn the pump off again and remove the cover screws so you can pull out the key assembly.
  4. Check the spider gasket for damage. If it is loose, you can use silicone or super glue to attach the loose rubber to the valve body’s dry grooves. If the spider gasket has more damage on it than just loose rubber, you should replace it (see tips below).
  5. Check the spring, too. The spring inside of the key assembly may also be causing the waste port of your multiport valve to be leaking. If you notice that there is not any tension when you push down on the valve handle or if it seems floppy, then the spring inside your key assembly has failed. This can happen over time due to chemical corrosion. You should check for rust under the lid of your key assembly near the spring.

Important note: Never try to stop leaking from a backwash line by gluing a valve on it. Doing this can cause water to bypass the filter, causing poor filtration and even worse problems if you forget to open the backwash line before backwashing.

How to Replace Your Spider Gasket

As I have mentioned, the spider gasket is responsible for directing the flow of water in your multiport valve. To replace your spider gasket, follow these steps!

Step One: Scrape It Out

Use a small, sharp, flathead screwdriver to scrape out the spider gasket. Make sure you also scrape out any small bits of rubber the old spider gasket may leave behind. Clean the surface of the gasket groove well and let it dry completely before installing the new spider gasket.

Step Two: Glue the New Spider Gasket

Ensure you also get the right size of replacement gasket, as they can vary. Then, with the flat side down, glue your new spider gasket in place, making sure to dab silicone or super glue in the dry grooves. Be sure to add the glue in a continuous line without adding any to the sides, as this could cause overflow and leaking in the future. You should also take a moment to wipe off any overflowing glue.

Step Three: Replace Key Assembly

Finally, put the key assembly back over your spider gasket and tighten it in place. Turn the valve handle to the nearest setting (filter or rinse) and wait at least 24 hours to let the glue dry before using it again.

How to Replace Your Key Seal Assembly

As we mentioned above, if water leaks from your waste port, you must repair or replace the key seal assembly.

Step One: Remove the Screws

To replace the key seal assembly, remove the screws from the top of the key cover and handle assembly.

Step Two: Remove the Handle

Tap out the pin connecting the key seal assembly to the handle. Then, remove the handle and valve cover. Remove the washers, C-rings, O-rings, and spring.

Step Three: Replace Everything Onto New Key Seal Assembly

Apply silicone lubricant to the O-rings and attach them to your new key seal assembly. Add the C-ring under the top O-ring and a washer to the stem. Then, add the spring and a second washer. Push the valve cover back onto the stem and add a plastic washer on top of it.

Step Four: Replace the Handle

Align the handle with the valve cover stem and push it in to compress the spring. After that, tap the handle pin back into place and align the valve body and cover assembly before screwing it back into place. You can also buy a pre-assembled key seal assembly!

How to Replace Your Valve Spring

As we said, a broken valve spring may also cause your waste port to leak. If the handle of your multiport valve seems loose or floppy, the spring is probably damaged since it provides the tension that pushes down on the valve rotor to seal off your multiport valve’s compartments.

  1. Just remove the pin to remove the valve handle and the key assembly inside the multiport valve.
  2. Remove the cover of your key seal assembly.
  3. Replace the spring and stem O-rings.
  4. Make sure you put the rotor and cover back in the same direction they were when you are reassembling everything.

How to Replace Your Key Cover and Handle Assembly

If your valve spring is working fine and you are not having issues with your key assembly, you may have to replace your key cover and handle assembly to resolve the internal issues your multiport valve is experiencing. To do this:

  1. Remove all the screws from the top of your handle assembly and key cover.
  2. Make sure the inside is clean and clear from all debris before adding your new key cover and handle assembly.
  3. Apply silicone lubricant to your O-rings.
  4. Correctly line up the key cover and handle assembly with the bottom of the valve, and press it on before tightening the screws back in place.

How to Replace Your Complete Multiport Valve

If you have tried everything else and seem to be experiencing many internal problems with your multiport valve, or the valve body is cracked, you should just replace the entire multiport valve. Here are the steps to replace it entirely.

  1. Simply disconnect the plumbing and their fittings from your return and intake lines.
  2. Remove the screws of the clamp holding the multiport valve in place and lift it off your filter.
  3. Before you reattach your new multiport valve, apply some silicone lubricant, line it up with the standpipe inside your filter, and make sure your plumbing ports are lined up with your plumbing.
  4. After that, screw the clamp back onto the base of your new multiport valve and reattach your fittings and plumbing back onto your return and intake lines.

Check out my article on pool multiport valve replacement costs for average prices on popular models and factors that go into replacing it.

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Look After Your Multiport Valve

No matter the issue you may be experiencing with your multiport valve, whether completely damaged or leaking, there’s usually a common culprit you can fix. If you need more help, make sure to call a professional (especially if you are replacing the whole unit). For more valve tips, head over to my main guide on pool valves.

Questions? Let me know.

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