Get a filter pitcher and reusable bottles.

 Invest in a pitcher or faucet attachment to have fresh filtered water readily available. Another option is an in-home water cooler with a water container that can be refilled locally for under a dollar. Invest in a wide-mouth washable drinking device (or two) as well. When you walk out the door, always be sure to have water with you. The key here, though, is to be sure you don't misplace your bottle since it is not disposable!