When discussing fiberglass swimming pools with perspective customers one of the most common misconceptions is that they pop out of the ground. Mostly, this fear mongering statement comes from the vinyl pool industry. It really is sad that the facts can be so distorted and so inaccurate. The truth is simply this:
Anything subject to water pressure, more commonly know as water table, can be moved upward if proper engineering and drainage systems are not created on the installation. If a swimming pool, septic tank, house foundation or anything else contained in the ground does not have some drainage system to relieve the ground water pressures, it can be subject to damage. While in most all cases, when a swimming pool is filled with water, it is not nearly as susceptible to damage. There are very rare cases where a pool will pop, gunite, vinyl and fiberglass are all subject to the same damage to ground water that was not correctly eliminated or controlled.
No pool, vinyl, fiberglass or gunite should ever be drained without assuring that no ground water is present. In most all of the know cases where swimming pools have lifted out of the ground, the pool was drained without proper consideration of water table.
When building a swimming pool, if at all possible a drain out to daylight is preferred as this will eliminate any ground water from collecting. In cases where this is not possible, a horizontal perforated pipe at the deepest end of the pool surrounded by stone and fabric routed to a larger vertical riser outside of the pool deck area. This is then covered by a skimmer lid and access to will always be there in the event the pool must be drained for some reason.
So, now you have the facts, and when a less than honest swimming pool salesperson tries to convince you differently, you will be armed with the truth.