Most pools are usually built with a hydrostatic valve at the deep end of the pool. This allows water into the pool should the ground water pressure be great enough, although it is unusual for this to occur. If a small amount of water is coming through, remove the top of the valve and fit an approximately 1m long PVC pipe over the outlet. The water will raise up the pipe until the pressure is equalized, and will keep the surface of the pool dry during maintenance, preparation or application of coatings