Dan,
The attached article describes how the folks in Bermuda have collected and cleaned water for 100's of years. Might be a good starting point for some further research.
Bermuda Cottages BTW, that's one place in which I'd love to bug in, er, out, whatever. I've been lucky to have spent a lot of time there, a wonderful place with friendly people and beautiful vistas.
Interesting future thread, how do you cope if you're on vacation and disaster strikes?