Hydrostatic pressure is a threat not just to fibreglass pools but also to any underground vessel, like septic tanks or oil drums. The constant push of groundwater against subterranean fixtures may cause significant hull damage if little or no force inside the fixture pushes against it.
Many pool builders believe backfilling the area around the pool is enough, but good installations rely on more than one system. The backfill can be accompanied by a simple dewatering system, consisting of a rigid PVC pipe and patio access. An external pump may be lowered onto the pipe base to draw out groundwater.
Although dewatering systems may not come in handy until after many years, it’s best to have one just in case. To save on installation costs, experts recommend a removable pump instead of a fixed one, like a sump pump. Having enough water in the pool to counter the hydrostatic pressure is enough, but heavy rains can increase the pressure, warranting a drain.
If you notice the liner slightly above ground, groundwater underneath the pool may be pushing it up. The PVC dewatering system is a great way to restore hydrostatic balance and, thus, give you peace of mind that your pool is well-protected from groundwater, especially when you have to drain it.