How much water to drink while running is a contentious issue: While it’s important to stay hydrated, it’s also possible to drink too much and induce hyponatremia, a potentially fatal condition that occurs when you drink a lot, sweat, and end up with a sodium imbalance. Increasingly, experts say the best way to manage your hydration is to drink according to your thirst.
If there aren't places to stash water bottles on your routes, or even just a couple water fountains, you might want to check out the Nathan Speed 2R pack ($35). It comes with a lightweight, adjustable waist belt that holds two eight-ounce fluid bottles shaped for easy one-handed grabbing. Because the bottles are small, they won’t wiggle around much, and the belt also holds a few gel packs or other accessories. (A $5 bill for Starbucks on the way home, for example.) The Speed 2R comes in several sizes.