Mysterious water in empty pool

[thekatocat]

I have a gunnite pool built in the mid 80's that has been empty for about 1.5 yrs. waiting to remodel in the spring. the pool is the backyard of a hillside property in phoenix, backing up from the pool is a natural dirt wall with another property sitting above ours. For the last three days their sprinkler heads have been leaking water from the lawn above and the water has been soaking in to the ground/dirt wall. There has been some obvious erosion from the dirt as water is seeping out of the wall.

My question/mystery is that I noticed accumulation of an inch of water at the lowest part the otherwise empty pool. we are positive that the water did not overflow from the dirt wall, over a block fence, over the deck and down the empty walls of the gunnite pool. Rather the ground is so saturated that it has come from below, underneath the gunnite. The only suggestion of this is evidence of wetness surrounding each one of the in floor cleaning heads spread through out the floor of the pool. My hope is that the water has just traveled underneath the gunnite and pushed up through in floor cleaning heads rather than some how found its way into the pump and filtration and otherwise closed system? any ideas on how to problem solve this mystery. It all might be moot after we remodel it (resuface, new pump/filter, and replace pool valet heads) in the spring.

[PoolDoc]

Obviously, you don't live around here! We've had enough rain, so that the question would be, "Why is there ONLY an inch of water?".

That's partly the problem -- water explanations are very local -- not just to the area, but to YOUR pool. If you can, a knowledgeable LOCAL service guy is going to be able to guess at the right answer a WHOLE lot better than we can here.

[mas985]

You may have a hydrostatic valve in your main drain and when water builds up underneath the pool, it opens the valve and lets water into the shell. This is done on purpose so that when the pool is empty and there is water under the shell, the shell won't float which can destroy the shell.