Big surprise, bottled water isn't doing the planet any favors. There are a bazillion reasons why not to buy bottled water. Here a few reasons off the top of my head:
1. It's WATER. As in, you can get it out of your tap for pennies.
2. Most bottled water comes from the tap. (So why the hell are you paying $1 or $2 for it? Get a real water bottle, and refill it at your own tap, where it probably won't come already tasting of plastic.)
3. Those plastic bottles end up in landfills.
4. Again, it's water, people.
"Clean, healthy and pure? Hardly. Bottled water is killing the planet
And our thirst grows, with 154 billion litres drunk in one year."
By Jon Neale and Jonathan Thompson
Published: 12 February 2006
Here's a snippet of what we can read without subscribing:
"A major new study has concluded that [bottled water's] production is seriously damaging the environment.
It costs 10,000 times more to create the bottled version than it does to produce tap water, say scientists. Huge resources are needed to draw it from the ground, add largely irrelevant minerals, and package and distribute it - sometimes half-way around the world."
So, again, why not just buy a Nalgene? (Although I'd recommend stainless steel -- Nalgene's new bottles are made out of #7 plastic (polycarbonate), which can leech bisphenol A, a chemical that interferes with hormones such as estrogen. Although it doesn't seem to pose a huge health risk, you definitely don't want to put your Nalgene in the dishwasher!)