I sweat so much I have to drink lots of water. Yesterday I rode 98 miles and I drank 6+ large bottles along with a qt of Gatorade and a qt of root beer with lunch. Lunch was 1/2 of a large sub sandwich and a bag of chips. I also had 2 granola bars and a chocolate covered peanut butter thing.
It wasn't hot so I didn't get dehydrated. On a hot climbing day I can drink a lot more water.