Have a sink hole in inground pool


Apr 22, 2019
New england
Hello . I have an inground pool which has been a nightmare since we bought the house last year. It was losing 400 gals a day last summer and I finally gave up on it in the fall. I figured the water would eventually stop dropping where the leak was. I had two pool guys come in, dyentest, pressure test the lines and listen underwater with a mic. So it dropped almost 3 ft over the winter and we could not cover it because of the low water lever. All of a sudden around jan/feb, it stopped leaking and started filling itself back up(from rain/snow). By the time spring hit I had to pump it down. So in late may I hooked everything back up and it was fine for a few day then the leak came back worse. Was losing almost 800 gals a day. So I started ripping the deck up. Found a bad leak around the skimmer gasket to pool and also skimmer was cracked. Replaced all that. Still losing water. I ripped up the dedk over where the pool light was and dug down. Found a big leak. The light housing had a 1/8 hole torn in it from when the light was broken. Plugged that leak . Found a small hole innthe liner(liner is 5 yrs old) and patched it. We think that happened when a cement block fell in pool. Water loss got better but still losing 3-400/day. Did my impersonation of Rambo and crawled under the deck(very creepy. Found snake skins, dead animal bones yuk..) to find a crack in the staircase leaking. Fixed that with some underwater jbweld. Finally😅😅 the leaks stopped. No water loss for over a weak....now today I discovered a sinkhole on the downward slope from shallow to deep end approx innthe middle. Sinkhole is about 4-5 inches around and approx 2-3” deep. I coild not see any hole innthe liner. I probably lost a total of 6-7000 gals . There are bumpy and rough spots all over under the liner but this is the first sinkhole. I dont think any piping would be under that slope so I suspect its from all the lost water. Any way to fix it without draining the pool(would be over 15000 gals to get halfway down the slope) plus I doubt the liner could be removed and put back in. I was hoping to either live with it or if someone knows another way...I was thinking of poking a small hole in the liner in the middle of the hole and try blasting some spray expanding foam then patch the hole but then after thinking on that , the chemicals in the foam may melt the liner....ideas or thoughts ? It is a 16x32 inground. Can the liner hold in the sinkhole ? It does feel like one side of the sinkhole maybe on a flat rock. I dont think this liner was installed over proper sandy material.


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
What you describe as a sinkhole I describe as a divot. I think of a sinkhole as something that can swallow a car.

I would leave it alone and hope it doesn’t expand. And save for a liner replacement .

@jimmythegreek thoughts?
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TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
Morris Cnty NJ
Its erosion from all the water loss. With a 5yo loner theres not much you can do. Either replace liner amd fix the hole, or pump down amd cut it out, patch the hole, patch liner, and refill. No easy way around a big divot
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