Coca-Cola Co. (NYSE: KO) and PepsiCo Inc. (NYSE: PEP), which are betting that people's thirst for bottled water will continue to grow, would probably prefer that the public ignore an experiment that Penn and Teller did on their Showtime series a few years ago.

Using hidden cameras, the magicians videotaped unsuspecting people at a restaurant who were being served glasses of what they thought were expensive bottled water by a steward. What they didn't know was that their beverage came from a hose. The program is called "Penn and Teller [explicative deleted]," which is exactly how I feel about the bottled water business.

The hype around popular brands, including Vitaminwater, whose corporate parent Glaceau Coke recently agreed to buy for $4.2 billion, fizzes upon closer inspection.

While there are people with bad water and unsafe water, most Americans have perfectly fine water coming out of their taps. In fact, as FastCompany points out, the two leading brands, Pepsi's Aquafina and Coke's Dasani, are purified municipal water. The Natural Resources Defense Council and other experts have repeatedly pointed out that bottled water isn't as strictly regulated as tap water. An NRDC study actually found that 33% of the waters it tested "violated an enforceable state standard or exceeded microbiological-purity guidelines, or both, in at least one sample."

"There are very few differences between the health benefits of bottled and tap water except in isolated circumstances," said Greg Kail, a spokesman for the American Water Works Association, a trade group representing operators of water systems, in an interview. "In North America, we all enjoy some of the safest drinking water in the world."