Bottled water is retarded and horrible for the environment. 4 out of 5 times in a blind test, people prefer tap water to bottled water. Tap water is more tightly regulated and costs 1/1000th what bottled water costs.
Oh and the best part? Most bottled water comes straight from tap water anyway.
If you need the convenience of bottled water you should buy a Nalgene or something similar and reuse it.