There are circumstances that necessitate draining. You should not attempt this unless it is absolutely necessary and you are thoroughly familiar with the steps necessary to do this safely. Draining your pool can cause serious damage to its structure. Why is it dangerous to drain a pool? Let’s explain this by the type of pool and the damage that can occur.
Inground Concrete Pools and Fiberglass Pools
Most inground fiberglass and concrete pools are built structurally to withstand the weight of the dirt against them when drained. However, if the ground water is high enough, it can push the entire pool out of the ground. The pool shell acts like a ship and floats up in the ground water.
Inground Vinyl Liner Pools
This type of pool is the most dangerous to drain and should only be done by a professional. Modern vinyl pools have been designed and built to hold the weight of the dirt without water in the pool. Older pools may not have been built structurally to hold back the weight of the dirt against it when the pool is drained. This can cause the walls to collapse. These pools were backfilled with dirt as the water level came up, equalizing the pressure as it fills. The next problem you must deal with is ground water which can make the liner float away from the wall as the level in the pool gets equal to or lower than the ground water level. Ground water must be lowered below the bottom of the pool by pumping it out through the well point line installed during construction. No well point line? Then you will need to install at least two one on each side of the deep end to pump out the water. Even if there was not any ground water present when the pool was built, this can change over time.
After draining, the liner can shrink which may then tear when refilling. The older the liner, the less it will stretch when refilling. Do not drain the pool in cold weather as this also reduces the stretching capability of the liner. After draining, complete your repairs and begin refilling as quickly as possible. As the pool is refilling, you may need to shift the liner around to make sure it is aligned properly. You will need to do this with only an inch or so of water in it because the weight of the water will quickly prevent you from being able to shift the liner.