I have a rental property with an in-ground pool. Last year my tenants failed to let me know that water was leaking out of the pool. They kept filling it up and once the pool was closed in the fall it all drained out. It wasn't until the following spring I found out there was no water in the pool upon opening.
I have a pool company that opens and closes the pool each season. They were able to find the holes in the liner, patch, and slowly fill the pool back up. Now I just found out that the foundation of the pool is shifting and I wonder if this problem is due to the pool sitting empty for so long.
Also want to mention we live in Canada where the ground freezes over the winter and the pool sat empty during the long cold winter. I've attached photos of the pool. Can someone tell me if this could be the reason for this issue?
Best Answer
I used to install pools with Zonolite / Portland cement mixture, later years Gunnite. The shells were usually only ~2" thick. That area had a high water table and if someone drained the pool the bottom shell would break and water would enter between the liner and the Zonolite/ Gunnite mixtures. If there were leaks in the liners they usually found a crack and could also cause the problem your pool has. We would drain the pool in the late summer pull back the liner and fill the depressions and cracks with hydraulic cement. If water gets between the liner and bottom be very careful filling the pool because this can rip the bottom drain out. I would suspect the leaks caused the problem. Even if this is a thicker bottom once the earth and sand are eroded the bottom has no strength.