As long as he eats a varied diet (there is a lot of fluid in food, even meat) and drinks fluids of any description - tea, squash, juices, pop - he will be perfectly healthy.
Thanks Ethel, i was kinda worried the other way, we recently had a weekend away and spending all our time together i noticed that he drank lots, and went to the loo lots and lots too, so yesterday i measured how much he drank and it was approx 2.5litres and was worried that it was maybe too much if there is such a thing as too much?
Get him checked out to be sure but he is probably OK. I have always drunk loads and am always at the water tap, so is my son. It's just the way we are. 2.5 litres is not excessive in warm weather if a child is energetic. Those people that have died from drinking too much water were drinking far in excess of this.