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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.

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

  1. What I love most about this article is your sense of humor bc after 3 hours searching, it’s still leaking so I came back to reread your info. (All great) I am still determined!!!

  2. Ha! Well, at least you’ve made me smile a bit as I am beginning to understand the challenge ahead. Good to have some clear expectations, albeit, even if it isn’t good news. Thanks for the advice! Wishing me lots of luck as I go on the hunt. If I’m not too annoyed, I’ll try and remember to give an update! thx!

  3. Well the first paragraph brought me to tears and laughter. I’ve checked my equipment and truly believe it’s my 20 years old liner. Yes I said 20 years. So after all I’ve read at least I got my money out of it.

    1. If you have a leak from a bottom drain, that’s usually a tough fix. Take off the cover and see how tight the screws are that hold the ring. If loose, tighten and recheck for a leak. If tight, you’ll have to change the gaskets which won’t be easy.

      My advice is if you are changing main drain gaskets, drain the pool down to about a 6″ depth first. There are two gaskets. Replace them both. Main drains usually leak because there is dirt in some of the screw holes which are preventing the screws from tightening the ring. Check for this by making sure each screw tightens all the way down. If you have some dirt in the holes, clean them out. It won’t be easy!!

      Once you know all holes are clean and the surface of the main drain is clean, replace the two gaskets and tighten the ring and refill the pool immediately.

      Thanks
      Dan

      1. Dan it is in the middle of winter Ice and snow …we closed the pool in fall everything was good. We noticed water under cover was getting lower, looked all around pool , no water anywhere so we put water back in pool (at this time 30* out) a couple days later it was down again. Called a pool place and they suggested to keep water in it, at least 2 feet Well we did this. It is now 2 months later and we looked out and the pool is empty, cover has fallen to the bottom on top of the ice and snow. No water hose , frozen in pool. Will the pool fall in?? Please any suggestions? We decided before this happened we were getting new liner so that’s that just affraid will fall in.
        Please help
        Peggie

  4. Is it possible to have a leak between the skimmer box gaskets? The guy that did the plumbing was absolutely hopeless and came back 5 times.. I noticed that the gasket on the outside under the skimmer is pinched and can’t be seen in the centre .. I can’t find any holes as it’s a new pool but I’m seeing wet soil 1 meter kind beside the skimmer box on the ground and not near the pipes underground .. hope that makes sense

  5. I have the same problem and now it is Spring and the pool is gross. Getting in it is not an option.

    My leak is presumed to be about 3 inches of below the skimmer as that is where the water has drained down to. Heavy rainfall brought it above a line I marked and then it came back down again after a day or two. I am thinking of removing the top rails one by one and using a compressor to blow air carefully between the lining and the wall of the pool. I am thinking if there is a small leak that it will presumably blow bubbles out a tiny hole that is somewhere. Thoughts? Crazy?

    1. any luck with the air compressor leak detection ? I also thought this might work but haven’t tried it yet

  6. We just installed our new pool after many days of preparation. After getting about a foot and a half of water in it we discovered a leak. Water was seaping out over the pool ground cover. After trying the food color with no luck I attached a plastic drinking straw to the end of a nozzle with a on the air compressor and worked it Between the liner and ground cover. Guess what? Bubbles came up from under the pool. May not work for all depending on where the leak is it it’s worth a shot!

    1. I love this!!! Thank you!! We just set up the pool and same thing, a little water leaking out. I’m going to tell my husband about this!

  7. I found the leak on the bottom of the pool liner. Just wanting to know if there’s a way of fixing the leak without having to drain the whole pool.

  8. I am pretty sure some of the seams on my brand new rectangular intex pool liner are leaking. All of the puddles forming around the middle on one side, and at the end all coincide with seam joints. Since my inspection of the inside of the liner with red food color showed no indication of the color being leached through the seam joints, I was wondering if laying several yards of white muslin flat under the problem areas, then filling the pool to 12 or 18″ then applying lots of blue color or dye in those areas and waiting for a couple of days to empty the pool. Then, carefully inspecting the muslin as I lift the liner looking for blue hot spots where the dye may help indicate where the leak is originating. My only question would be how do you patch a seam? Should I cut a square the entire width of the seam and patch it like a large hole, or should I try using that liquid seal stuff in the quart bottle? I thought I read somewhere that the liquid leak fix isn’t for above ground vinyl liners…only in ground liners. Any suggestions are greatly appreciated

    1. I really don’t think that will tell you much but hey, you never know. Water from leaks can travel away in very strange ways so it’s really hard to determine where a pool is leaking based on the outside of the pool only. You said this is a new Intex pool? I say contact the Walmart you bought it from and get them to send you a new one. They have millions of those landfillers and Walmart will take back or replace just about anything.

  9. after 4 days looking for the leak I followed your instruckions and you said to be patient and most leaks are at side wall bottom I calm down took my time and found the leak at the side wall at the bottom less than 1 hour thank you soooo much your the best!!!!!

  10. I’ve only come to terms that most likely I have a leak.

    The soil next to my pool is SUPER saturated. I tried building it up because it’s the lowest part of my yard.

    It’s only worse now. The level in the pool has dropped consistently.

    Does it make sense to focus my attention on that area of the pool?

    1. It would make common sense to concentrate on that area but we are talking about a leak. And sometimes with water leaks, common sense doesn’t work. Check out my article on how to find a leak in an above ground pool and good luck.

  11. We have a leak, but it only started when we changed our skimmer. So, my husband took it out again and reinstalled it, still a leak. Then he decided to change the jet, still leaking; but the leak stops just below the skimmer. We have no wet areas around the pool, but we have some wrinkles in the liner at the bottom that were not there before – could this be where the leak is?

  12. Could I have a
    Problem with termites or nut grass? I have tiny holes in the bottom of my liner. Also does it matter what thickness the liner is when ordering a new one. We have only had this one two years but we ordered it online instead of buying it at our local pool place.

  13. We have a softball size sinkhole in our not even year old liner. We have a gorilla pad under the new liner and the pool company cut the old liner and left that as a base too. How could I have another sinkhole? I’ve checked this area for over an hour for a hole of any sorts. I do not see one. Suggestions? The only way to fix it is to drain it and pack the sink, but from reading all over the internet, they say not to drain an existing liner for fear of it shrinking. I’m at wits end w this pool. I’ve talked to 2 pools companies and they botht said to leave it. How bad is this for my new liner?

  14. Above ground 24′ pool – square skimmer – water leaking out of the ‘cutout guides’ to use when using a rectangular skimmer. Replaced skimmer gaskets – used food coloring – no leaks found. Taking a guess that leak is high on the wall and water is working its way around the pool between the liner and the outside wall and leaking out at rectangular cutout guides. Looked carefully going around waterline 3x but nada – will continue to look – does it sound like I’m on the right track ?? Thanks for any and all advice.

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