Water loss

[Nathan J]

For the last several years, we have experienced water loss of 1/2 inch up to an inch a day in our inground pool. At least 3 different professionals have done pressure testing with no luck in finding a leak. This year, the pool was not losing water, until last week. Yesterday it lost 7/8 inch. Any ideas on why it would hold water for 4.5 months since opening this year and then start losing again?

 

[Nathan J]

Update - bucket test completed today. 11 hours with pool pump on. Pool lost 3/4", bucket lost zero. What's going on?

 

[Flying Tivo]

Its called a leak. I would try it again without the pump running to see if its on the pressure side. It will slow down with pump off.

 

[Nathan J]

Update #2 - 13 hours with pump off, pool lost over 1/2 inch. I realize there is a leak, but why would the leak that had been present in the past stop leaking for nearly 5 months and then start back up again?