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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. Victoria Avatar

    HiI have a multiport and have put it in the Recirculate mode and after 2-3 hours I have lost 2-3″ 1/2 tile of water out of the Pool , why is that happening?
    Thanks

    1. Matthew Simmons Avatar

      A few things come to mind. Your multiport’s spider gasket could be out of place or torn, allowing water to release out the waste line. Or, your multiport’s spring is damaged causing water to release out the waste port.

      Or, you have a large leak in your pool basin or plumbing. Dye Test For Swimming Pool Leaks

  2. John Avatar

    Pool still drains after the valve is in FILTER position. Pool built in 2009, only upgrades are the pump & heater. I shut off the main power.

    1. Matthew Simmons Avatar

      When you describe it as draining, do you mean water is pouring out of the waste line? Or, are you describing a leak possibly sourced from your pool plumbing or basin?

  3. Zach Avatar

    My pool won’t prime, someone told me that my multiport was defective and that is the reason because some water was coming out of backwash when it was in circulate mode.
    The pool was working fine when I opened it
    But I was backwashing an awful lot due to how dirty pool was then it started losing prime when I would turn pump off. So I would reprime every time to turn on. Then it completely stopped priming at all. That’s where I’m at now. Do you believe the multiport needs to be replaced. Thank you

  4. Ralph Avatar

    Need help with a leaking Jandy 3 port valve in the suction line. When the pool is turned on the leaking stops but it sucking in air. The issue is that I can’t just replace it. The pool is built 3 feet above where all the equipment is and there is not shutoff to the suction lines. The skimmer and main drain lines go directly to this diverter so if I try and replace it the water gushes all over the place. I’m planning on having a professional replace all of them in the fall when I close the pool but for now I’m just looking for a quick and easy (affordable) fix to this so that we can use the pool for the next 2 1/2 months which is how long summer lasts in New England. The leaking is from where the top of the diverter is screwed into the base. Any ideas or suggestions?

  5. Sherrie S Avatar

    Hi We have had our above ground pool for 20 years. We always take the valve cover off for the winter and put it back on in the spring with no issues. We just purchase a brand new filter and valve, 19 in Blue Devil. It is leaking between the valve cover and tank. We have taken the top off twice and made sure the gasket is in place. The second time we did this it did not leak for hours and then it started leaking heavily at the side gaps of the flange. We can not figure out what we are doing wrong. This flange does not come completely together like our old flange and we are afraid to keep tightening that we may damage it. Any input is greatly appreciated.

    1. Matthew Simmons Avatar

      If this filter is brand new and it is already leaking then you have a defective unit. Contact the company from you purchased the filter to have them replace it immediately.

    2.  Avatar

      I’m guessing it’s not as likely with the newer filters, but found on my previous, older filter that even though the filter cover COULD physically be put back on without any specific position/alignment to the base and wouldn’t leak normally wouldn’t leak, upon closer inspection I discovered that there actually WAS a very slight notch/slot in the cover that needed to be aligned to the bottom,base flange to ensure the cover and flange met completely together, with no leakage, but when it DID started leaking slightly once again, several months later, after checking seals, etc… I finally noticed, then, that there was a nearly invisible fine, hairline crack on the inside wall of the lower/bass piece… Good luck!

  6. Anita L Rushlow Avatar

    I have all original equipment since my inground pool was built in 2006. The pool company came to open the pool this week. I was out there talking with them much of the time. When I was asking questions they were rude. They said they knew what they were doing. I told them that I needed to know what they were doing since I keep a log of all things related to my pool in a notebook. I left for a bit and when I came back they handed me the pressure gauge. They told me it was stuck at 10 and it was broken. They replaced it with a cheap plastic one. I noticed right away the new one was leaking! I told them I never had any leaks at the pressure gauge. They did not ask my permission before they replaced the pressure gauge. If they would have asked me I would have told them that it sticks at 10 when the pump is shut off, but it always registered the proper pressure, i.e. 20, when the pool was running. Then they applied some white stuff and told me it would “cure” Well the leak went from dripping to a steady stream. They told me there is a crack next to the pressure gauge. I believe they broke it when they wrenched off the “bad” pressure gauge that had been there since 2006. I am so pissed! Now I need to get an entire new multi-port!!! What do I do? Do I take them to small claims if they refuse to fix what they broke? They knew I was right inside the house and they still didn’t try to reach me via text or come to the back door to show me what they were replacing. If they had, I would have known exactly how this new leak happened. I am livid!

  7. RB Avatar

    When I move the multiport to backwash losing water from the filter which starts to fill when pump is switched on. Multiport lid contains a built in gasket which looks fine. Also can hear gushing sound in multiport when on filtration . Any ideas on cause

    1. Matthew Simmons Avatar

      Did you check the valve’s diverter spring? Is the multiport valve handle loose?

    2. Matthew Simmons Avatar

      Check the diverter spring. If the diverter spring is broken or displaced the diverter can lose its seal, allowing water to flow through the backwash. A sign the spring is loose is a jiggly handle.

  8. Philip Deforche Avatar

    Hi, I just installed a new TR60 sand filter and also a new Hayward HP 1.5 single speed pump. The problem I have is that the laterals in the sand filter keep on breaking and I have a lot of sand in the pool …. I have had to replace the broken laterals already 4 times and every 2 weeks one or two break ….. I have no idea what can be wrong for the laterals to break? Can it be that the multi vale is not working properly? This is the only part I haven’t replaced… Or do I put too much sand in the sand filter? Any help would be highly appreciated. Best regards, Philip

    1. Matthew Simmons Avatar

      A multiport valve is not going to cause laterals to break. I would look into how you are installing the laterals. One of the most vulnerable times for a lateral is when you are adding sand to the tank. That is why we suggest filling the tank halfway with water to the laterals do not take the full brunt of the weight as sand is poured in.

  9. Kate Hamilton Avatar

    I’m not entirely sure how, but the pin on our Hayward Multiport Valve came out on one side and now the valve can’t sit where it’s supposed. Getting the pin back in is proving to be a pain, though! I’m having difficulty getting it to line up to be able to go through. When I noticed the valve wasn’t seat properly and the water level in the pool was dropping, I turned the pump off. Since turning the pump off, however, the water level has dropped all the way below the skimmer level. Could water still be draining out even tho the pump is off?

  10. Jim Avatar

    Hi, I have just installed a brand new vari-flo SPO714T over top of my Filter (S244T) and when setting the dial into the preset groove for “backwash” it doesnt work (no water flows out). However when i push down on the handle and move it slightly more clockwise (out of the grooved position) it works fine.
    Is this an issue with the spider gasket? Faulty Valve?
    Thanks!

    1. Matthew Simmons Avatar

      That seems like a faulty valve, especially with it being straight of the box. I would contact the dealer to get a replacement, ASAP.

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