Despite probably the cleanest tap water supply in the world, Americans are increasingly turning to bottled water. In fact, the average American drank more than 12 gallons of bottled water last year. And that’s expected to increase this year, according to the International Bottled Water Association (IBWA), the trade association for bottled water manufacturers. With the growing concerns about the safety of drinking water and the advertising imagery of pristine springs, the trend toward drinking bottled water is not a temporary fad. The question is whether drinking bottled water is worth the extra cost.

In its recent four-year study of 103 brands of bottled water, the Natural Resources Defense Council (NRDC) found that one-third contained levels of bacteria or carcinogens that exceeded purity guidelines. NRDC is a national, nonprofit organization of scientists, lawyers and environmental specialists.

"Bottled waters do not generally pose a major public health threat," says study author Erik Olson, a senior attorney at NRDC. "Most water is free of contaminants. But just because you buy your water in a bottle doesn’t mean it is any safer, purer, or better than what comes out of your tap," he says.

A key NRDC finding is that bottled water regulations are inadequate to ensure either purity or safety, although both the federal government and the states have bottled water safety programs. At the national level, the U.S. Food and Drug Administration (FDA) is responsible for bottled water safety, but the FDA’s rules completely exempt waters that are packaged and sold within the same state, which account for between 60 and 70 percent of all bottled water sold in the United States.

IBWA said the environmental group "is trying to scare consumers with its report on bottled water," and charges that NRDC’s own testing shows that levels of chemicals of concern were either below detection limits or well below all applicable standards. "For the past 37 years there have been no confirmed reports in the United States of illness or disease linked to bottled water," said an IBWA statement.

Nevertheless, the NRDC is calling for more stringent federal regulation of bottled water. "If people are going to spend up to 10,000 times more per gallon for bottled water, as opposed to what comes from the tap, they have a right to know what’s in the water, where it’s from, and that it’s absolutely pure," Olson says.

The NRDC study also found that between 25 and 40 percent of bottled waters are simply repackaged municipal tap water, in other words, what you are paying good money for might be available free from your tap. Olson adds, "Bottled water is essentially regulated on the honor system in most states. There is no requirement that water be tested in certified labs. Bottlers are not required to report to known standards violations. And unlike tap water suppliers, bottlers need not disclose to consumers known contaminants in their products."

IBWA disagrees. According to the IBWA, consumers can trust that bottled water is safe. In addition to FDA and state regulations, members of the IBWA, who produce about 85 percent of the bottled water sold in the United States, must meet strict industry standards established by the trade association. These standards, contained in the IBWA "Model Code," exceed the FDA regulations currently in place for bottled water, according to the IBWA. To ensure that all their bottled water is as safe as possible and of the highest quality, all IBWA members use one or more of the following practices: source protection and monitoring, reverse osmosis, distillation, filtration, ozonation, and disinfection.

So how do you find out if the bottled water you buy is safe and pure? "Most times you would have no idea," Olson says. "The consumer is left out in the cold."

A few tips that might help:

Unless you prefer the taste of your bottled water, "stick with you tap," Olson says. And if you are concerned about your tap water’s purity, filters can remove certain contaminants, he says.

"Buy filters certified by NSF International," he recommends. Even more important, replace the filter at least as often as recommended by the manufacturer, Olson says "Otherwise guck can build up, the filter can’t take it anymore and contaminants leech out in the water and you’re worse off than ever."

The most popular containers for bottled water are transparent, flexible plastic bottles. If you choose bottled water to avoid chemicals in tap water, you could be trading them for the plasticizers that have been known to leech into the water. There is no data that these are harmful, but they are related to other compounds that have shown unhealthy effects. Solvents used for cleaning the plastic bottles are also found in bottled water on many occasions, according to NRDC.

A valid, and popular, reason for buying bottled water is taste. From a nutritional point of view, however, there is no real benefit. Taste is the major reason, after concerns of purity, why people prefer bottled water over tap water. Chlorine is most often used to disinfect tap water, and can leave an aftertaste. Most bottlers use ozone, a form of supercharged oxygen, or ultraviolet light as the final disinfecting agents, both of which leave no taste or chemical trace.

If you buy bottled water, ask yourself whether it is really worth paying a lot of money for water that may be no better in quality than water out of the tap. But do your research and find out for yourself. Check with your local municipal water supplier for its water quality statistics. If you are particularly concerned about the quality of your tap water, call your state’s drinking water program or the EPA Safe Drinking Water Hotline (800-426-4791) for a list of state-certified labs. Many municipal water suppliers also will conduct free tap-water testing.

The IBWA offers a toll-free consumer hotline at 800-928-3711; IBWA’s Web site is at http://www.bottledwater.org. The FDA Web site is at http://www.fda.gov. NRDC’s Web site is at http://www.nrdc.org.