Best and worst bottled water brands

How much do you know about the bottled water you drink? Not nearly enough, according to a new report released today from Environmental Working Group(EWG). "Bottled water companies try hard to hide information you might find troubling," says Jane Houlihan, senior vice president of research for the Washington D.C.-based research and advocacy group.

[Read more: Cities with the best (and worst) tap water]

EWG analyzed the labels of 173 unique bottled water products and company websites to determine if companies disclose information on where water comes from, how or if their water is treated, and whether the results of purity testing are revealed. The nonprofit also looked at how effective (and advanced) any water treatment methods are. Researchers followed up by calling dozens of bottled water companies to find out which ones willingly tell consumers what's in their bottles.

The Environmental Protection Agency says on its website that consumers have the right to know where their water comes from and what's in it so they can "make informed choices that affect the health of themselves and their families." Tap water is regularly tested and consumers can find their local water info online. That's not necessarily the case with bottled water, which is not required to disclose that information to consumers. "Bottled water is a food product and every one of these companies is complying with federal law," says Tom Lauria, of the International Bottled Water Association.