Bottled water may be a multi-billion dollar industry in the United States, with Americans consuming an average of 28 gallons per person per year. But how much do people really know about what they're drinking? Not nearly enough, according to a recent study released by the Environmental Working Group (EWG).

The EWG took a close look at the labels and websites of 173 popular brands to determine if the companies disclosed where their water comes from, how—or if—it is treated, and whether brands revealed results to purity tests. Only three manufacturers received a passing grade—even when researchers (under the guise of concerned customers) called dozens of bottled water companies looking for information. So, what do these brands have to hide?

Could their water just be gussied up tap? I'm not saying I have any insider information, just asking. Personally, I jumped off the bottled water bandwagon long ago when carrying an Evian bottle became less chic and more eco unaware. It takes 1.5 million barrels of oil each year (enough to fuel 100,000 cars for a year) to satisfy Americans' thirst for bottled water. PET, the plastic used in water bottles, is made from crude oil, according to the Earth Policy Institute. Then there's the environmental waste (just in California more the 1 billion plastic bottles end up in landfills each year) and possible BPA contamination. I'll stick with my filtered tap and Earthlust stainless steel bottle, thank you.

You can check out the full report on the EWG's site, but here are six brands that scored particularly poorly.