Tap water? As if. Nary a hip, health-conscious chick would be caught dead putting anything less than bottled H2O upon her parched lip these days. With reports that most bottled waters aren't any better than tap ‑- and that some brands, like Dasani, are nothing more than water from the municipal supply ‑- beverage companies have upped the ante. By dousing their drinks with oxygen, calcium, vitamins and herbs, they're producing luxe libations that tout more than just hydration. So what's the 411? Is one more healthful than the other? Three experts weigh in on the designer water craze and tell us what to swig and why.

Joy Bauer, nutritionist in NYC and author of Cooking with Joy
Spring, mineral, distilled, purified ‑- there's really little difference. "Whatever you choose is fine," Bauer says. There is no health benefit to mineral-free water (or for that matter, mineral water). However, minerals are what influence the taste. "The bottom line is that water is great for us and we don't drink enough of it, so however you can get it in, go for it."

Does that include tossing back oxygenated waters like Penta? Well, for hydration, yes. But if you're looking to get an extra punch of energy, Bauer backs up recent research that says it's all a "big hype. It might make you a little broker, but it's not going to give you extra oxygen," she says. In a 2002 study, the Journal of the American Medical Association found that five brands of oxygenated water tested by researchers offered less oxygen than what's contained in a single human breath.