This actually happened to us last year but I wanted to see what everyone thought about this. We noticed that the liner in our deep end felt a little spongy. Last year when this happened we had a diver come and look for any leaks. No leaks. We thought maybe there was a leak in our plumbing somewhere but really we didn't have any indication of that around the pool. We had a reputable pool company come take a look and they said maybe some water was leaking through the bottom drain and we could try plugging it. We did that last year and eventually the water receded. We kept the drain plugged as you really can operate the pool without it. However we have water in the deep end again. This did occur after a heavy rain fall. We have sandy soil which won't really retain water. And the area around our pool slopes down and away. Our only thought is that maybe some water is getting in at the joints in our coping. We have a jewel shaped pool and some of the coping clips are missing. Does anyone think this is what's happening? Any other thoughts? The water went away on its own before so we aren't super concerned about that. Just wondered how we could prevent this from happening.