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Why Is My Multiport Valve Leaking?

Leaking Pool Filter Valve

Multiport valves are the main water route interchange for your pool water. If the water needs to be forwarded, reversed or drained out, it will need to be done through this valve. The routing system inside a multiport valve is essentially water’s equivalent to chutes and ladders.

These valves have as many as seven “positions” but for the most part the average pool owner will only use a handful of these.  Here is a list and explanation of the most often used positions so we have a solid footing moving forward: 

  • Filter – The standard operation mode; the water is cycled from the pump through the filter media and back to the pool.
  • Backwash – This selection is the cleaning cycle. The flow of the water is brought in from the pump  then routed to enter the filter reverse to the normal direction. This effectively begins to loosen and eventually eject dirt through the waste port.
  • Rinse – Rinse returns the normal flow of water through the filter but it maintains the exit flow routed to the waste port.  After a backwash some particles may still be left in the pipes so to avoid that dirt being ushered to the pool, we need to rinse.Picture1

The Spider Gasket

If the valve is the highway interchange of your water then the spider gasket would be the guard rail. These gasket spokes act as dividers to ensure the path of the water stays true.  If your multiport valve has a drip coming from the waste port line, most pool technicians will jump for the spider gasket.

The spider gasket is located either on the diverter pinwheel or the base of the valve the diverter faces.  When we select a function on a multiport valve and release the handle, we drop the diverter onto the spider gasket.  If the gasket has become worn and warped then the water will seep through the seam and end up in the waste.

The Fix: The solution is pretty simple, replace the gasket. Some gasket replacements are simple, remove the valve cover and old gasket, then lube in a new one. Other gaskets are glued into the diverter which requires a few extra steps.  If you want a step by step guide on the different ways to replace a spider gasket read this: How to Replace a Spider Gasket on a Multiport Valve

The Diverter Spring

That tension we feel when spinning the selector handle is created by the diverter spring.  Besides making it hard to spin the handle, the spring serves the purpose of locking

Picture2the diverter against the spider gasket. If the spring in your valve is worn, it may be causing a seam between the diverter and gasket which shows itself in the form of a leak out the waste port.

The Fix: Replace spring, which to be honest, is not fun at all.  The spring is sandwiched on the diverter assembly which means it must be disassembled and assembled again. The hard part is getting the spring depressed enough to secure the handle pivot rod.  If you are feeling brave and want to attempt a spring replacement, please follow our guide: How To Replace a Pool Multiport Valve Spring

Valve Cover

The valve cover o-ring is found in the seam between the valve cover and main housing.  If water is found leaking from this seam then this gasket would be your culprit.  To access the gasket we would simply remove the 6 – 8 screws on the valve cover to remove it, peel out the o-ring, clean the groove, lube the new o-ring and re-attach screws.

The Fix: Read an inch above this line.

Valve to Filter Connection

Whether the valve is a top mount or a sidemount, it has to connect to the filter somehow.  At that joint connection there is a gasket holding on for dear life.  Because of the high flow at these connections, a blowout is somewhat common and easy to spot.

The Fix: Remove the valve from the filter and replace gaskets. Hopefully, the valve is piped in with unions so its removal is not a pain in the neck.  Once the valve is off, find the gasket and apply a freshly lubed replacement.

Thanks for skimming through our pool musings. If you have any further questions about pools, valves or otherwise, feel free to give us a call at 877-372-6038.

author avatar
Matthew Simmons Technical Writer & Pool Product Expert
Swimming pool expert at InyoPools and host of Poolside Chat, brings over a decade of experience in the pool industry.

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119 responses to “Why Is My Multiport Valve Leaking?”

  1. Amanda Avatar

    I have a sta rite sand filter and it is leaking slowly out the waste port. It will stop when the filter is set on recirculate, but is leaking when on filter. Any suggestions??

    1. Matthew Simmons Avatar

      Our entire article is filled with suggestions. Did you give them a try?

  2. Kari Avatar

    Hi. We have a Hayward Series Vari-Flo XL. We have been having problems with our filter not properly filtering and now we have an algae issue. We noticed when vacuuming the pool green was coming back into the pool. My husband took out all the sand, checked the later assembly intake valves and then replaced the spider gasket. When putting everything back together; we now have water coming up from under the handle. Help! My daughter is having her 8th birthday party in 3 days. Any help would be appreciated.

    1. Matthew Simmons Avatar

      The two problems are separate issues. If you have green water going into a filter, green water is going to come out. You need the shock your pool, and add algaecide to kill the algae. Read/watch this guide: How to Clean a Green Pool?

      And you are seeing a leak from the multiport valve handle because either a gasket or gasket is broken on the diverter stem. Or they were dislodged as you were servicing your filter.

  3. Tim Avatar

    I have Pentair filter. When filtering, I have a leak coming through the hole in the stem of the air pressure relief knob. The local store says to replace the whole valve. Is there a way to fix the leak instead?

    1. Bonnie Avatar

      Tim, did you find something to solve your problem? Mine is the exact same as yours. I was able to solve it a few years back by bet this – putting crazy glue around the top part of the hole where the pressure valve goes in but this year that isnt working. I really dont want to buy a new one!

  4. Todd Harrison Avatar

    Matthew, I have a 12,500 Gal salt water pool with a Pentair 1.5 HP pump and a Pentair SD-80 sand filter with a 1.5″ multiport valve. The valve handle is on top of the sand filter and I have noticed while the pump is running in the filter position the MPV leaks around the handle, haven’t noticed this that much in the backwash or rinse positions but its probably as bad too. Also the handle seems to have a lot of play in it. The sand filter also drips from the drain plug in the bottom and the sight glass, not bad but if I am going to fix one thing I might as well fix em all . Otherwise the filter cleans the water and holds pressure fine, I think its the spider gasket and spring but don’t know how to go about replacing it, isn’t there a certain procedure to follow?

    1. Matthew Simmons Avatar

      The handle problem you are describing sounds like a bad diffuser spring and/or diffuser stem part. In the diagram below, in Box 1 we see all the parts contained on the handle-to-diffuser assembly. The Spring marked as Key 8, the Washer as key 7 or The o-rings as key 9 are likely bad are all things that can cause the leak or the handle to have too much play. We have guides on how to fix the problems in on DIY section.

      How To Replace a Pool Multiport Valve Spring

      1. Todd Avatar

        Matthew I don’t see a diagram, I looked at the diagram for the Sand Dollar filter but it only lists a box 1B which is the full Multiport valve and does not break it down to the diffuser parts.

  5. Robin Buccheri Avatar

    My filter is leaking when I turn it to “Rinse” after I backwash–everything else is fine.

    1. Matthew Simmons Avatar

      Have you checked the spider gasket like I mentioned in the article?

  6. Geoff Horton Avatar

    Hi,
    I have a Waterco T600 filter and it nearly drains my pool when its on filter,and if i put it on waste it drains but at the same time you can see the dirty water returning to the pool.Could this be the spring on the multiport valve?
    Geoff

  7. Nick L. Avatar

    My spider gasket and the diverter spring failed on my Hayward VariFlo XL valve, so I purchased a new valve to replace it with. After removing the 6 screws I pulled off the old valve and installed the new. I noticed that there was no gasket between the diverter and the multiport valve housing. After tightening down the bolts in a star pattern I had a lot of seepage coming from that seam. I cannot seem to stop it completely. I removed the valve, cleaned the mating surfaces thoroughly and applied a layer of plastic epoxy between the two surfaces. After curing the leaks are mostly gone, however I am still getting a slight leak from one area between two screws. Could the mating surface of the multiport housing be warped or should there be a gasket between the two surfaces? The new valve didn’t come with one, nor did the old valve have one installed.

    1. Matthew Simmons Avatar

      There should be a gasket to seal the seam between any two individual pieces of the valve. The two main gaskets are the spider gasket, that resembles a wagon wheel and the valve cover gasket. The valve cover gasket sits between the valve cover and the valve’s housing. Without these gaskets, you would see significant leaks.

      Here is the parts breakdown for the Hayward Multiport Variflo XL 1 1/2″ SP714T

  8.  Avatar

    If there is a leak in the multi purpose valve, could this cause the creepy not to function? There is leaking around the valve handle, bubbles shoot into the pool (but no jet of water) and there is no suction on the creepy.

    1. Matthew Simmons Avatar

      The multiport valve is on the pressure side of the system, so it should not cause your Krauly to not work. Have you checked the cleaner’s hose for air leaks, or the cleaner’s disk and foot pad for excess wear?

  9. Stephanie Avatar

    Spring is not slack at all. The cloudiness started about 2 weeks after the new filter was installed. I thought it was a chemical issue at first. Chemicals are perfect according to a local pool store. The first time I used the waste was this past weekend. Thats when I realized the water was going to waste and returning to the pool. Before that though i was noticing sand returning into the pool but I thought maybe because we had just changed it out that it was normal. Now more and more is coming in.

    1. Matthew Simmons Avatar

      Because you are getting sand in the pool, you may have a lateral or standpipe issue but that does not explain the water going the wrong way. Before you had the water diverting issue did you remove the valve cover or check the spider gasket?

    2. Yong Menh Avatar

      Was the MultiPortValve brand a CMP product? They had huge issues with the entire line of valves and have never been able to fix the quality issues. Buy OEM always……cheap product is well just cheap product…. i.e. CMP

  10. Stephanie Avatar

    Help!! I have a brand new Hayward S210 Pro Series Sand Filter. When i try to send my vacuumed water to waste, the water goes to waste AND returns into my pool! I can’t get in touch with Hayward. Wait times to talk to them are 20 plus minutes. My water is extremely cloudy so I used floc in it and now can’t vacuum it out because some dirty water is returning to the pool. Sand filter is only 40 days old!! I’m hopeful its a warranty issue but I can’t get in touch with Hayward to find out. Spider gasket looks good and so does the spring.

    1. Matthew Simmons Avatar

      Is the spring on the multiport valve slack? Also has this issue been happening since you installed the filter or is the issue relatively new?

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