My water bowl is on some tiles left over from a project. What I would like to do is have a larger pan, like one of those black rubber things and put a rigid but durable and porous thing on top, then put the bowl on that, so any spills could drain into the pan. Then wetness would be contained. I saw this idea in a book. Maybe there could be cinder blocks holding up the edges of the flow through surface so the chickens couldn't flip the whole thing.
Since winter has finally arrived, I'm going to try a water dish inserted into an old tire, stuffed with straw and see how that works.