Liter for liter, bottled water costs hundreds of times as much as the stuff that gushes from the tap, but otherwise it isn’t so different—except that it’s subject to a good deal less monitoring, says Peter Gleick, author of Bottled and Sold. In fact, between 25 and 45 percent of the bottled water sold in the United States originates as tap water. Maybe that’s why some manufacturers make such extravagant claims:
It’s “oxygenated.” Some bottled brands supposedly contain up to 40 times as much oxygen as conventional water; ads say the extra oxygen improves athletic performance. But scientists who tested five brands of oxygen-enriched water found no performance boost—not surprising, the researchers say, since a single breath contains more oxygen than a whole bottle of oxygenated water. All you get from oxygen-enriched water is an expensive burp, says Gleick.
It’s “structured.” For years, the manufacturer of Penta water claimed its water had “30 percent smaller molecular water clusters” that hydrate you better. The company has backed off on some of those claims after being challenged by British regulators, but Penta still says its water may help prevent disease and lengthen life—with no accepted scientific evidence to support that idea, Gleick points out.
It’s a “diet aid.” Can drinking bottled water help you shed unwanted pounds? Yes and no. Drinking lots of water can promote weight loss. But you get that advantage with any kind of water—whether or not it’s enriched with vitamins, minerals, or other ingredients.