My overflow pool loses about 10 ton of water every 4 days so i have drained it and have taken the main drain cover off and i keep getting water coming out of the concrete round the plastic main drain into the empty pool, the bottom of the pool is well above the water table. If water comes out does that mean i will lose water from the pool when it is full? Should the concrete around the main drain be sealed? It seems the concrete around the drain has disintegrated and no longer encases the main drain. Can anyone offer any suggestions?