It wasn't especially warm this evening, and I rode 24 miles or so before I took a drink. On the other hand, on Monday, I rode 33 miles or so, and had finished 2-24 oz bottles and a 32 oz bottle by the time I was done. The reason you're not thirsty after nine miles is because you live in Denver and not Houston. Get a good ol' sweatbox of a place to ride in, and you'll go through the liquids, too. Also, fat people can go through a lot more liquid than thin people, so if you're fairly fit, you may need half the water I do to ride the same distance.