In the 1940s, scientists figured out how to turn crude oil into something miraculous: polyethylene terephthalate, or PET—the plastic that would one day be used to make disposable water bottles. It turns out that oil and water do mix, and very profitably: In 2006 Americans spent some $16 billion on bottled H20.

But there's no good evidence that this water is any safer than what comes out of your tap. The EPA requires stricter testing of the public water supply than the FDA does of bottled water.* And water purchased at the store is in many cases plain old tap water, filtered, bottled, and sold for a price that's often higher than the cost of gasoline.

Bottled water isn't merely a waste of money, however. The Earth Policy Institute estimates that it takes more than 1.5 million barrels of oil a year to make water bottles for American consumption—and less than 15 percent of the bottles are recycled. It also takes energy to transport all that water: According to the National Resources Defense Council, shipping water from Italy, France, and Fiji to New York alone yields about 4,000 tons of carbon dioxide emissions each year. The water may be pure—but the end product certainly isn't.

* If you're worried about the quality of your tap water or your pipes, consider buying a filter certified by NSF International ( Be sure to properly maintain all filters, including the popular Brita, or you risk making your water worse.