Researchers at the Pacific Institute in Oakland California ran the numbers and found that bottle production alone wastes 50 million barrels of oil a year (that's 2.5 days of US oil consumption). Add to that energy the energy needed to process the water, label the bottles, fill the bottles, seal the bottles, transport the bottles, cool them prior to sale… well, you get the idea.
Bottom line: Bottled-water drinkers in the US alone in 2007 squandered the equivalent of 32 to 54 million barrels of oil. Triple that number for worldwide use. For perspective, imagine each bottle is one-quarter full of oil.
As reported at Treehugger: Bottled-water drinkers are the new smokers.
Since oil and water don't mix, turn on the tap. Still want a container? Try reusable Nalgene or stainless steel. Not without impact but durable at least. Traveling overseas to the lands-of-unclean waters? Pony up for a Katadyn bottle/filter combination. I can personally attest that this all-in-one system is a miracle worker of good intestinal and environmental health.
Concerned about the one in six humans who must live in the lands-of-unclean waters? Consider tossing a doubloon or two at the LifeStraw people who've found a nifty and inexpensive way to survive deadly water supplies.