[Porsche-O-Phile]

Not directly, however rain water can potentially wash the leeched out chemicals into the bottom of the pool, where they'll be pumped to who-knows-where. Redwood is a good finish material - termite resistant and pretty durable. There's also a bazillion different synthetic finishes that can lay on top if one is concerned about nail heads or screw heads eventually starting to back out/stick up, etc.

Overall I really like Wayne's concept. It's a neat idea and not something one sees every day, but as with such things there are issues that have to be addressed also that aren't the "everyday" variety.