Lots of good input here and especially many comments about water. As someone who has often backpacked and ridden in arid areas, it has always been obvious to me that we occasionally confuse thirst with nutritional needs. If water is scarce and you don't want to waste it, drink a moderate amount, but before you chug the whole bottle, think about when you last ate. We often made a concoction called a "gordita" in South American desert areas. Mix a half cup of raw oatmeal, no difference between instant and regular, with an appropriate amount of water to make a slushy (no heat necessary), add a tablespoon or so of sugar and a bit of Koolaid powder (you get to choose the flavor). Its like a tepid milkshake, but it meets your sugar needs which may actually keep you from drinking more water than you needed. This is not a replacement for water, but instead a way to meet your body's need for an energy boost that you may be confusing with thirst. Try it on the road when you a beat, its not as good sitting in your living room.
A head wrap under your helmit is also a good evaporative cooler. Don't go without the helmit, after all the styrofoam is an insulator.
And for when you have a bit of water to spare, don't be afraid to take that juice bottle, poke a nail hole in it which is then plugged with a match stick. Hang it in a tree and take a shower in 1 quart of water, pubs, hair, and all the rest. We all waste to much water at home but on the road you can shower with a quick wash and rinse and it improves your outlook tremendously. Tom