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Finding a Leak in an Above Ground Pool

I have really good news and really bad news when it comes to having a leak in an above ground swimming pool. The really good news is that once you find the leak, it’s usually super easy to repair. The bad news is (yeah, you probably guessed it) finding the leak is difficult. Locating a leak in an above ground is so difficult that I don’t offer it as part of my services. Even if it’s the off-season and I’m broke, I’ll turn down a job to detect a leak. There are many cases where the leak is never found in an above ground and the only solution is to replace the entire liner. So now that I’ve scared you and lowered your expectations, let me give you some instruction on how to find a leak.

Check the Pool’s Equipment First

To check the pool’s equipment first is the easiest. When looking for a leak in an above ground pool, the hardest place to find it is somewhere in the vinyl liner. To avoid any frustration, inspect the equipment first (even if you have a feeling that the leak is inside the pool). Follow this checklist first. The leak may be outside the pool.

  1. Clean the equipment areaHayward Pro & VL Series
    If the pump/filter area is cluttered or overgrown, clean it first. Pull out all the weeds and store the pool toys, outdoor items and rocks/mulch away from the equipment. If there is an ant pile that formed under the pump, kill the ants and clean area.
  2. Turn on the pump
    Some leaks will leak more when the pump is on. Since it is easier to see a bigger leak, you’ll want the pump on.
  3. Inspect the general area for signs of wetness
    Water is wet. Duh! So it stands to reason that any signs of wetness are your best signs for a leak.
  4. Look closely at everything
    When I say closely, I mean get down on your hands and knees and look at all the components, hoses, fittings, and lids for drips. Sneaky leak alert: Pay close attention to the area directly underneath the pool’s pump. Pumps have shaft seals that can leak straight down into the ground and sometimes there will be no visible ground moisture.Have a dry towel handy in case something is questionable. Wipe the area dry and inspect for any new signs of wetness to appear.
  5. Inspect the skimmer and return at the wall
    The pool’s skimmer box and return are two common spots for leaks. Water travels downward due to gravity. Duh #2! Because of this, look directly under the skimmer box and return as that is where the leaking water will travel. If you are not sure, again use the towel to dry the pool’s wall and reinspect for any signs of newly formed moisture.Don’t be in a hurry; take your time. Some leaks are deceiving and require patience to find. If you’ve checked out all these spots and have come up dry, it’s time for the real fun.

Tips for Finding a Leak Somewhere in the Vinyl Liner

This may not be an easy task. The best piece of advice I can give here is to be patient.  A leak can be anywhere inside the pool and there is not one soul on the planet that can find some of these so don’t be too hard on yourself if you don’t find it quickly. Here’s what I do listed from first to last:

  1. Turn off the pool pump and let the water get completely stillYou’ll need to be able to see the bottom of the pool as clearly as possible while you are standing outside of the pool.

    torn above ground pool liner
    I Think I Found the Leak
  1. While you are standing outside the pool, inspect the pool’s bottom all the way around
    Most above ground pools have sand or earth based bottoms and coving. When there is a leak in the vinyl, the water usually leaks out in the ground somewhere underneath the pool. In most cases (but certainly not all) the leaked water travels through the sand/earth bottom and causes the earth to wash away leaving small valleys or divots or holes in the pool’s bottom that was once flat. Some of these washed away areas under the pool are visible and will tell you where the leak is in the liner. If you see something like this, it’s time to get in the pool (SEE STEP 5).
  1. Check the outside of the pool
    Didn’t see anything while you were following the previous step? OK, then while you are still outside the pool, you better check the outside bottom of the pool. If it’s covered, dig around the wall at the bottom and expose the bottom track. This is the tracking that the pool wall fits into at the bottom. Clear away any mulch or rocks or dirt so you can easily see if there are any signs of excessive wetness next to the track.What makes this tricky is that your ground may hold moisture naturally so just because you find some wet ground doesn’t mean it’s a sign that there is a leak in that area. Look for signs of excessive wetness close to the pool as a sign for a leak.
  2. Time to get in, but first clean the pool
    Before you consider getting in the pool to find a leak, clean and vacuum it. You are looking for a small hole in the liner so dirt and leaves sitting on the bottom will make it tougher to find. Make sure the water quailty is good too. Swimming in a slimy, cloudy pool sucks. Have a good dive mask or goggles and some kind of applicator that is filled with a food coloring or dye. Also, it would be really nice if you have a diver’s weight belt to keep you down in the water. Again, before you get in make sure the pool pump is off.
  3. Get up-close and personal
    A hole can be anywhere in the liner, but most of the time the hole is at the bottom close to the pool’s wall. Put on your mask, take a breath, and swim to the bottom getting up-close and personal with the liner. Closely inspect any of those small valleys or divots you saw earlier for small holes. If you see what may be a hole, shoot some of the dye you have from your applicator around the area and see if the dyed water draws into the hole. If it does, voila, you have found a leak.

So you checked at the bottom of the pool all the questionable areas of the pool liner and found no hole. The next place to check is all the way around the pool where the wall meets the pool’s bottom in the same up-close, methodical manner. Still no leak? Now in the same way check the pool wall starting at the bottom and moving towards the top.  Most wall leaks are lower so spend most of the time at the foot at the bottom of the wall.

If you still haven’t found the leak, it’s time to play manta ray. Very slowly swim very close along the bottom (like a manta ray) inspecting every square inch of the pool liner. If at any time you see something that may be a hole, shoot some dye in the area and see if the dyed water draws into it in order to verify the leak.

Now you’re over this. You’ve searched the pool’s bottom like a sand shark for a couple of hours and you look like a prune and didn’t find anything. Well, that sucks! I really feel your pain. The last thing you can do is allow the pool to drain without adding water. It will stop at the point of the leak and make it easier to find, but not always. At this point it may be time to get a new liner. I’d say if your liner is five-years-old or older, then go ahead and get a new liner. When liners age, they may start leaking in several spots as they become brittle.

The last thing I can offer you is good luck finding the leak. Sometimes that’s what it takes.

author avatar
Dan Dougher

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77 responses to “Finding a Leak in an Above Ground Pool”

  1. Elizabeth Avatar

    I forgot ask what I originally posted about. What is your opinion on “Pool Fix a Leak” or “Lo-Chlor Leak Sealer”, “Jack’s Magic The Purple Stuff”, there are different ones? Thank you again.

  2. Elizabeth Avatar

    Hello Dan, We have a 21′ Round 54″ that I think started leaking very slowly from when we bought it and sit it up in June of 2019. It has only been up maybe 6 weeks. The leak got worse, my husband Dan had put the seals on wrong on the Inlet so maybe it was evaporation at first??? That fixed it, helped but still leaks. It has stopped about 4″ below the Inlet.
    There are dibbits too but we have the 21′ gorilla pad and the 18′ one from the old pool under it. He made a border and put ground cloth down with small stones so it is near impossible to check the outside. He tried but it is wet likely because of the weed cloth. So I am thinking the leak is where it stopped draining but you said the upper wall is unlikely. There is about 6000 gal of water left of the 10,000 gal that it holds.
    I thought of trying the Air Compressor method but with no water there it would be hard to tell if there is a leak at each section. Maybe feel for air coming out for the upper part and it may reveal something for the underwater part?? Also the thin back method of moving it along the bottom.
    I called a repair person but $50.00 Service call alone and my husband is close to retirement from a Foundry he has been at for 47 years. We live week to week. He got this for me, I am 72 and have had pools of some sort most of my adult life. It brings me Peace. Your page is wonderful! Thank you! Any ideas?

  3. Karen Avatar

    Dan, I have a huge oval above ground pool. It’s 15 years old and still has original liner. Just little faded. I was walking around the pool yesterday and saw a little spot of rust on my side near the bottom and a tiny trickle of water was barely running down the side. Doesn’t even make a puddle. Do you think the leak would be close to wear it’s coming out the rust spot?

  4. billy Avatar

    is there a chemical that you can in the pool that will settle where the leak is I have been at this leak for 2 week now empty the pool 3 times and still no luck lots of water leaking on the grass this is hopeless I have tryed everything . what is this air compressor test all about and how do I do it

    1. Steph Avatar

      Any luck on the air test ?

  5. svu2002us Avatar

    We have a Summer Waves 18 x 48 above ground pool, this is the 2nd season for it. Filled it up and discovered a leak around the hose drain plug near the bottom! We have even drained it down, dried it and patched it. No good, patched also on the outside. We have tried several different sealants and vinyl trying to patch it. As soonn as we put water in (even after waiting to the next day, it leaks again. We have never used that drain plug, we have a pump we use to drain it. So there hasn’t been any excessive force used on it. Any ideas or suggestions? We can’t afford to keep filling it up!

    1. Dan Dougher Avatar

      What did you pay for it? Like $300? Those pools are cheap and the majority of them last only one season before hitting a landfill. Just buy a new one.

    2.  Avatar

      We used Flex tape on ours and it worked.

  6.  Avatar

    I started opening my pool yesterday. The water left in the pool over the winter (I live in Canada where 25C below 0 is common) was dark green – usually it’s fairly clear when first opened – so I added degreaser and then shock and added fresh water to the proper level (half way up the skimmer). It started to clear but is still murky today. Connected all the hoses and started it up. Everything seemed fine. I turned off the pump overnight. This morning the water level is down 6 inches! Can’t see any hose leaks or any leak from within because the water is still too murky. Around the outside perimeter of the pool I see no wet areas. Any advice? BTW, your article is great.

    1. Dan Dougher Avatar

      If the pool level just dropped 6″ after you hooked it up and worked on it, then it’s something you did. Unless it’s a coincidence that a major leak popped up at the same time you started working on it. Not likely.

  7. Nancy Avatar

    Question: My husband bought a new pool cover last year. We haven’tbeen able to find one that lasts for very long. During the winter, he drains the water off of the top of the cover. Is that a good idea? is it possible that we don’t have a leak at all, and that he is draining water out of the pool? See is firm in believing that the cover is not porous, and I believe that he could have been draining water out of the pool. Our water level is two and a half feet now. Thoughts?

    1. Dan Dougher Avatar

      If your water level is only 2.5 feet, then you have a leak.

  8. LISA Avatar

    When I opened my 3 year old above ground pool, the water was lower than normal. There was only 25 inches in it. It is 56 inches high. We got a lit of rain this winter and spring so it was hard to tell if it leaked out. Somehow a bird managed to get under my cover and had drowned…of course. I fill it up ,long story short I have some dripping outside the pool. It’s not really affecting my water level..yet. I used the dye near that spot, and got nothing. I’m very disappointed. Especially only having 3 seasons of use out of it. It is my happy place. I have had Walmart pools, a fraction of the cost, that lasted longer. I’m going to try the pladtic bag mentioned in an earlier comment and be a sand shark and inspect every centimeter. One thing I have noticed is around the edge of the pool the sand has give and I have a little ditch about halfway around pool.. Could this be the culprit? Thanks in advance for any input!
    Lisa

    1. Arlene Avatar

      Did you get an answer yet?

  9. Mark Avatar

    My above ground pool leaked half way down during the winter and there are no puddles around the bottom of the outside of the pool. Why would that happen?

    1. Dan Dougher Avatar

      There’s not nearly enough information here for me to determine why. This is like asking why we only got five inches of rain last summer.

    2.  Avatar

      You must have a small leak somewhere.

  10. Dave L Avatar

    My 18′, 48″ above ground pool is leaking. I found a couple leaks by cutting up a plastic shopping bag to make a flat rectangle. Then I used a pool brush that had a handle long enough to reach the bottom to push the plastic sheet against the bottom. I moved it slowly across the bottom and when it went over a leak, it was drawn down into the leak. The slight suction from the leak held the plastic bag against the bottom. It worked fairly well, but I still have another leak somewhere. I can’t reach the middle of the pool, and it is too cold to get into it now.

    1. Dan Dougher Avatar

      Good story. Thanks for sharing.

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