Dry by Neal Shuterman and Jarrod Shusterman
It was being called the Tap-Out. As in, nothing left; it was all gone. Only most people had no idea it was coming. Well, a few had an idea. After all, there had been water restrictions to make sure that people weren't wasting water. Like no more private swimming pools, and of all things - water balloons! But really, who would have thought that one day when you went to turn on the water, it simply wasn't there...at all!