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.
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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.

77 thoughts on “Finding a Leak in an Above Ground Pool

  1. we live in st. louis and our above ground pool liner has a slow leak. it is too late in the season to get the liner replaced. is it better to leave the pool uncovered or to cover it for the winter? currently it is uncovered and has about 3 feet of water. i am worried about the walls collapsing in.but with rain and snow i don’t think it will drain completely before next spring and a new liner.
    would the best advice be to leave it uncovered and just wait and see?

    1. If the water level stops dropping, I’d close it like you normally would any other year. If it got you through those other years, it should handle this one. You want to keep an eye on the water level to ensure you’re not still losing water.

      Do you know where the leak is in the liner? If you can find the leak, apply a temporary patch to hold you over until spring.

  2. Hi Dan. have an 18′ round pool and the water leaked continually after I had lowered the water for winter. The water level continued going down, down, down till the last 6 inches froze. I am assuming it would have totally drained out had it not frozen. There seem to be little trenches. Would that help narrow my search down? When the thaw comes what would you recommend I do to pinpoint (ha ha! that’s probably what I will be looking for) the leak? Is there a product that could seal it?

    1. I’m trying the dye. Cant find it yet. My pools almost empty at this rate. I hope that will help me find it! My pool is 3 only months old 😭


  4. I just set up a 21′ pool everythig went great liner was good started filling it up and no leaks until I got to the skimmer. I put the skimmer on then I realized that I did not attach the back part just the wide mouth part so I pulled it off and of course the liner stretch and when I went to re mount it the orginal holes where lower. But I thought the gasket would be cover it. Well filled it up and I got to leaks one at the post to the right of the skimmer and one at the post to the left. Inside I could see it dripping in the track. So I lowered the lever today to see if it stops. just not sure what todo the outlet is also next to the skimmer so could they both be leaking on the inside? I look at the liner under water and could not find any problems. I was going to pull face plate off the skimmer and silicone it. I have spent 4K on this pool and now I am freaking out that if i just let the thing leak the uprights will start to drop. Not sure what to do HELP!!!

  5. Hello, Your blog has been super informative during our DIY pool install. We followed your guidance on the linear the pool looks amazing until we started filling it and saw water!!!! The water is near a post and we can’t find a leak so far – it has been two days since we started filling it. The pool company suggest we wait two more day to see if the water is from the pressure the pool is creating on the earth. The dirt pad is new. To prep the pad, a tree was removed and other foliage. Then the dirt was compacted, during the compacting, it was watered and compacted again. Do you think the wet dirt coming from the post is related to the compacting process?

  6. I have an 18 round above ground pool.The winter cover is still on and the pool only has 2 feet of water in it..The 2 feet of water is still remains the same.
    Would the leak be in the liner itself and with losing that much water over the winter I must definitely have a leak somewhere in the liner?

  7. Hello Dan, I live in a Philadelphia rowhouse. My neighbor outback has an above ground 18’ pool. His property’s elevation is at least 1’ above mine. It is landlocked back there with cyclone fences separating properties. All properties are supposed to have drains. He is a new neighbor & doesn’t do as much pool maintenance as the prior homeowner of 35 yrs. Today, I noticed many, many white stones from his yard had cascaded down the slope into my yard. Happened overnight. My question: If pool liners have un-repaired leaks, can those leaks rip & tear open? Am apprehensive about suddenly getting 1000’s of gallons of water in my yard and prolly my house. Thank you for any information.

  8. Hi dan, I put up an 18” above ground Intex pool. Puddles of water are forming beneath the pool. I saw little droplets of water on the outside of one of the seams next the where the puddles were. Should I try putting a patches down this seam? Is it worth doing the dye test?
    The puddles only form during the day after people have been in the pool and they are not there overnight? Please help!

  9. Dan the real pool guy really doesn’t install pools well at all I had my brand new pool Installed 4 months ago by Dan and has been leaking for over a month. Really quick to blame the pool owner. Bad install from the beginning. Be aware

  10. 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.

  11. 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?

  12. 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?

  13. 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

  14. 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!

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