How To Empty Your Swimming Pool Properly

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Established 1999

by Bill Nash
®Bill Nash

*How to Empty a Fiberglass,
Gunite, or Concrete Swimming Pool Guide

Every swimming pool built or manufactured must, at one time or another, be emptied for repair or resurfacing. There is no such thing as a pool that will never need to be drained, regardless of what you may have been led to believe.

With this in mind, almost every type pool listed above has some method of relieving the underground water pressure. This is a safety feature built into pools to prevent the hydrostatic pressure caused by underground water from damaging the swimming pool. We are talking about serious damage, so please take heed to the precautions I've listed.

Because fiberglass pools weigh the least, as compared to concrete or gunite, the danger of lifting is greater. In my 15 years in this industry, I’ve never had a fiberglass pool lift, however two gunite pools did "pop". So the possibility certainly exists. Use this information as a guide in an effort to prevent this problem.

Never empty a fiberglass pool during the rainy season unless the pool has a built-in system for relieving the underground water pressure (which most do). If you have standing ground water hours after it rains anytime during the year, there is a strong possibility that any pool (gunite or fiberglass) will lift.

Hydrostatic Relief Valves

If your concrete or gunite pool has hydrostatic relief valves (usually located near the bottom of the steep slope), remove them as soon as you can get to them while emptying the pool. If you have an operating bottom drain, remove the cover and see if it has a hydrostatic relief valve (almost all do), unscrew and remove the valve as soon as the pool is drained.

The last foot or so of water probably won't drain out, so be ready with a sump pump to immediately place at the drain to remove the remaining water. This is extremely important, and must be done quickly, so the bottom drain can be accessed for removal of the cover.

After opening the valve, place a pipe into the valve (about 3’ to 6’ long) and put a hose through the pipe, Bring the hose up over the top of the coping and attach a pump to draw the water from under the pool. This is just ground water, so there is no chemical content to be concerned about. Point the water flow to a drainage area away from the pool.

Stand Pipe

Some pools had a water problem during construction and, to the current owners good fortune, have an inconspicuous "stand-pipe" located 10' or 30' from the pool. The pipe is less than a foot high and may or may not have a cap, place a long hose into the pipe, then attach the hose to a utility pump and drain the underground water. Some are located under the diving board and some can also be located near the pump and filter.

Quite often, a stand pipe equivalent was used when the pool was built, and a high water table was encountered. You may have a piece of black or white PVC emerging from the ground on the side of the deck next to the grass. It should be slightly lower than the top of the deck and usually goes unnoticed. This PVC goes directly into a 4' by 4' pit filled with stone. This PVC serves the same function as a stand-pipe, and should be used as explained above.

Well Points

If you’re in a beach area or other low lying area, you may need to consider “well points”, but this is a last resort and is rarely necessary under other conditions. When well points are necessary, they should be installed by an experienced individual. Some pools require well points only on one side, while others must have well points around the entire pool.

*This article may be reprinted in its entirety with no omissions and with full credit to the Author.

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Page last updated on Wednesday, June 26, 2013