Jae Park, a professor of civil and environmental engineering at the University of Wisconsin-Madison, says that bottlers can use any of the techniques used by city purification plants, including treatment with ozone or ultraviolet light, filtration, and chemicals that cause contaminants to clot together and settle out. Some use no techniques, and some a combination of techniques. One chemical treatment that's out of favor among water bottlers, for reasons of taste, is chlorine. And partly as a result, says Park, "Drinking water is safer than bottled water."

Not so, says Stephen Kay, director of communications for the trade group the International Bottled Water Association (IBWA), who says bottled-water standards were tightened in the mid-1990s. And while the NRDC claimed that federal standards did not apply to the majority of bottled water, which does not cross state lines, Kay says the standards apply whenever the water, or even a bottlecap or label, crosses state lines. Still, two recent reports could raise eyebrows among the high-brows who get soused on water-in-a-bottle.

Bacterial broth
A bacterium that causes severe diarrhea in developing countries can survive in bottled mineral and spring water, according to a study published this year. Enteroaggregative Escherichia coli (say that three times, quickly!), was not in the water to start. But when the researchers spiked bottled water with the bug, it prospered, especially in water held at room temperature.

The results showed that "the source water for bottling industries must be kept free of contamination," the researchers wrote. They also recommended that bottled water be refrigerated to minimize pathogen growth (see "Behavior of..." in the bibliography).

Thus the dilemma: Chlorine added to city water kills organisms that cause disease. But the residual chlorine not only can taste foul -- it also makes tap water safe to drink even after it been standing in your glass for a week. Not so bottled water. "Bottled water is safe, but if you leave it for a day in the sunlight with the cap open, bacteria may grow," says Park, who teaches water purification technology at the University of Wisconsin-Madison. "But if you have tap water left in the same condition, bacteria cannot grow, because of the chlorine."

Bottle blues
An Italian study published in January detected chemicals that can cause mutations or cancer leaching from the PET (polyethylene terepthalate) bottles commonly used for many beverages, including bottled water. The researchers gathered non-carbonated and carbonated mineral water from a bottling plant and stored it in glass. Once a month they extracted chemicals from the water, and tested for any effects on DNA.

Curiously, two-month-old extracts from mineral water altered the DNA of test cells, even though samples stored for other periods did not. Using an analytical tool called a gas chromatograph-mass spectrometer, the researchers found that levels of a plasticizer known to cause liver cancer increased as water was stored longer in the PET bottles (see "Evaluation of the Migration..." in the bibliography).

Aside from the bottles themselves, the bottling plant also caused concern. The researchers noted that water sampled before it entered the plant showed little or no toxicity, compared to "very significant DNA damage in the water collected at the bottling plant."

But pure water could never be a bad thing, could it?

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