Not trying to hijack Nelly's thread, but I think the link I posted before is relevant to your question. I wouldn't drink that much water if I were you:
http://en.wikipedia.org/wiki/Water_i...#Notable_cases
I don't know how much would be a safe upper limit for the average person. Anybody have any thoughts on a max. amount?
In the absence of such a known upper limit I would err on the side of caution and significantly reduce the quantities you are using. For me even a 1/2 liter bottle is enough to make me go within an hour or so unless it's with food. Maybe start with that.