In BCT for the Army, in Ft. Jackson, SC, we had to drink 1-1.25 1 quart canteens an hour, in addition to one glass with every meal. Of course, this was in the summer... They were more worried about dehydration that overhydration. Shit, in the fall, we still had hydration formations in the evening. Made for great late-night wake-up trips to the bathroom. :)