[MediaMole]

In ground pools? What would happen to them? Serious question.

[PAR35]

Get enough water pressure under them, and they'll start to float. That'll tear up the plumbing, perhaps cause cracking. Then when the soil dries out, they'll drop back down, but probably out of alignment.

At some point, the only thing worth reusing is going to be the hole.

[PAR35]

Here’s a link:

Draining a Swimming Pool May be a Bad Idea
http://swimming.about.com/od/poolandspamaintenance/qt/drainswimpool.htm

[MinuteGal]

I saw a pool here in Florida which was left drained by unthinking, absentee owners. It rose up like a boat above ground level and then listed to one side.

Simply put, there's always underground movement and water pressures underneath pools. The weight of the water in a filled pool obviates this problem.

Leni