Leaking Inground Vinyl Pool

Hello, New member here with a problem. After quite a bit of effort I thought I had found the source of my leak, but now am unsure. Pool seemed to leak more with pump running. Seemed to be no leak with pump off and return lines plugged. Water was below level of skimmer and had still been leaking, so skimmer was not the problem. I thought I had it narrowed down to one return line. I excavated below the deck and exposed this line where it goes through the wall of the pool (formed plastic wall, pool and liner 9 years old). Water was leaking down outside face of plastic formwork where the fitting goes through the wall (Hayward SP1408 fiiting). After doing some reading it seemed like the flange was the likely problem. Changed flange and leaked about the same or worse. Then decided to change gasket. Still leaks the same, but I think I made a small hole in the liner next to the flange. Do not patch that yet other than a piece of tape.

Additional information. Leak stopped when water level was below returns (with pump on and off). When I pulled back the liner to change the gasket I noticed water behind the liner at about the same level as the water in the pool. Since the soil next to the pool was saturated I assumed this was leaking through the formwork, which I assume in not water-tight at the joints.

At this point I do not know what to do (other than patch the small hole). Pool company cannot come out for two weeks at least and suggested a diver first. If the water is not leaking when below the returns then a diver will not help.

I have tried dye testing around the returns and some other areas. No sign of movement of dye, except at the questionable return. When I have tested there it seems that the dye is pushed back into the pool, not into the flange joints or the pipe.

I would appreciate any suggestions. At this point I would be happy to pay the pool company, but after explaining this too them they did not seem to have any idea what to do, other than suggest the diver. The company I called built the pool. Thanks

I can only make some guesses. If by the "flange" you mean the nut that holds the fitting in, that's not what usually breaks in a return. It's usually the threaded plastic pipe...or the washers/gaskets are shot. But you may well have another source of your leak.

Do you have a bottom drain? That was the problem with mine. I had the pool company close the drain. Apparently it was damaged or cracked when the pool was not winterized properly.

Here is an update on my problem. Maybe it will help somebody. After lowering the water below the returns the pool stopped loosing water (with the pump off) , so that ruled out a leak in the liner below water level and ruled out a leak in the main drain. I tried testing the lines with air pressure, but the test plugs did not seal well enough. I then made a simple test setup to test the returns. I took a short piece of 1-1/2" threaded pipe and connected and elbow and about a 2-foot long piece of pipe. I screwed this into one return fitting and plugged the other. I then filled the pipe with water and timed how long it took to drain from the pipe. The pipe drained in about 20 seconds. After leaving it sit for awhile I filled the pipe again. It did not take much water, which indicated that the leak was probably close to the pool. I did the same thing with the second return. With that return the water leaked from the standpipe faster than I could fill it.

I decided to dig down to the return on that side of the pool. My concrete deck is only 3 feet wide side it was not real hard to dig down and over. The interesting think it that on the other side the soil was saturated. On this side the soil (clay) was hard and dry until I got within about 6 inches of the return pipe. Then it became very wet. Once I exposed a bit of the pipe I took a hose and placed in against the return with the eyeball fitting in place. I just held it in place so the pipes were not pressurized to the full pressure from the hose. After doing this for a short time I could see water flowing into the hole I dug from above (I had not exposed the area around the elbow). That is as far as I have gotten. I am certain at this point that it is leaking at the elbow in the return pipe. It is getting too cold to pull the liner back so I am going to wait until spring to fix it. It is just good to know where the leak is.

Another thing. I had dug down to the pipes adjacent to the pump since I thought that settlement of the equipment slab may have caused a problem there. If I could not figure out which line was leaking I had considered cutting one of the return lines at that area and installing a valve so I could isolate the pipes. I did not need to do this, but it would have been a relatively easy way of isolating one line at a time. I was thinking of cutting the bottom off of a plastic pool chemical bucket and burying this around the valve with the lid several inches below grade. That way I could access the valve relatively easily in the future if needed. I could also have piped the valve about grade, but I assumed that I would not really need to access it in the future.

Solved my problem. Turned out to be a leak at an elbow to a return on the opposite side of the pool than I thought. Apparently the water was working its way around the pool between the liner and formwork or behind the formwork and was showing up on the opposite side.

To find the leak I made a test rig consisting of a short pipe of 1-1/2 inch pipe (threaded in one end), a PVC coupling, and a two foot long piece of PVC pipe. I screwed thin into a return fitting and plugged the other fitting. I filled the standpipe with water and saw that it drained from the pipe in about 20 seconds. After letting it sit for a while I filled the pipe again and it did not take much water. That indicated that the leak was probably not far below the height of the fitting. I did this again on the other fitting and I could not add water fast enough to keep the pipe filled. I then dug down and over to expose this return pipe. My pool deck is only 3 feet wide so it was not real hard to do this. The soil on this side of the pool was hard and dry until I got very close to the pipe. I then put a hose against the return with the eyeball in place. I just held it there so that the pipes would not be pressurized to full water pressure. Although I had not completely exposed the pipe and elbow, water flowed down into the holes when I did this, so I am convinced that I found the problem. It is too cold to work with the liner this year, so I will fix it next spring.

Another point that may help someone. I had also suspected that the problem could have been at the underground fittings near the equipment slab since that slab has settled. I dug down to those fittings and exposed them. No problem there. If I had not found the leak I was considering cutting on the the return pipes there and installing a valve. Then I could have isolated the lines to see while one was the problem. I also thought about cutting the bottom off of a pool chemical bucket and burying this around the valve to provide future access.