You made me smile. I had similar experiences on my first century. I'll try to dig up a link to it for you.
Regarding water, here's what I've learned since. I try to keep two bottles full. When the first one's empty, I start looking for a spigot. I refuse to buy water. There's a hose somewhere. Churches, parks, and old gas stations that close in the evening(if you're in the middle of nowhere).
I've done a few centuries or longer rides(50 to 100+ miles) now, and I've never spent more than 5 dollars for food/water. That's a cheap way to travel. Develop a taste for oatmeal cream pies, over-ripe bananas, and peanut butter crackers.
If it gets late, a cup of coffee is nice. Sometimes a coke if I'm a few miles out and running out of steam.
But, yeah, keep up on water. What if that 10 miles had turned out to be 40?
edit: here's that link.
http://www.bikeforums.net/road-cycli...t-century.html