Nov. 7, 2008 -- Americans drank 9 billion gallons of bottled water last year, or slightly more than 29 gallons for every man, woman, and child in the country.
They also spent $22 billion on a product that critics of the bottled water industry say they should be getting for free from their home faucets.
Most of the criticism has focused on the environmental impact of bottled water. But an investigation released two weeks ago also raises questions about the purity and even safety of commercially available water.
WebMD looked into many commonly asked questions and concerns about bottled water. Here is what we found:
What did the new report find?
The Environmental Working Group tested 10 best-selling brands of bottled water for 170 contaminants and found different mixtures of 38 contaminants, including bacteria, fertilizer, and industrial chemicals at levels similar to those allowed in tap water.
Two of the samples, bought in San Francisco, contained the chemical compound trihalometrane in levels that exceeded the amount allowed in California.
"The bottled water industry really presents this image of purity, but our investigation demonstrated that it is really hit or miss," Environmental Working Group senior scientist Olga Naidenko, PhD, tells WebMD.
But the International Bottled Water Association, which represents most bottlers, charged that the group's report contained "false claims and exaggerations" and noted that the group's sample was not representative of the hundreds of bottled waters on the market.
Joseph Doss, president of the International Bottled Water Association, tells WebMD that California has much stricter contamination restrictions than the FDA. He says the state's allowed level of trihalometrane is eight times lower than the level allowed by the federal government.
How can I tell if the water I purchase started out as tap water?
Roughly 45% of the water sold in single-serve bottles comes from a municipal water source.
By law, bottled water that comes from a municipal water supply has to disclose this on its label unless the bottler takes steps to further purify the water, which most do. In this case, the label will say "purified water" or "purified drinking water," but the original source is probably tap water.
Water labeled "spring water" comes from an underground water spring, but it may be piped to the bottling plant.
"Mineral water" comes from an underground source and must contain no less than 250 parts per million total dissolved solids, such as salts, sulfur compounds, and gasses. No minerals may be added to the water by the bottler.
"Artesian water" or "artesian well water" must come from a well that taps a confined aquifer.
How can I tell if there are contaminants in the bottled water I purchase?
You probably can't. Tap water is regulated by the Environmental Protection Agency (EPA), which requires yearly public reports identifying the contaminants found in local water sources. But bottled water is regulated by the FDA, which has no such requirement.
The Environmental Working Group and the Natural Resources Defense Council, which released its own report critical of bottled water purity in 1999, want the FDA to require bottlers to list contaminants on water bottle labels.
In its report, the National Resources Defense Council noted that the EPA requires more frequent testing of municipal water than the FDA requires for bottled water, and that bottled water rules allow some contamination by E. coli or fecal coliforms, which indicate possible fecal matter contamination.
The report noted that the FDA does not require bottled water to be tested for parasites such as cryptosporidium or giardia; the EPA does require this testing for tap water.
Doss says consumers have a right to know what is in their bottled water, and they can find out by calling an 800 number that appears on every bottle. "If a consumer calls that number and does not get the information they want, they can and should choose another bottled water brand."
Does calling the 800 number really get you the information you want?
That depends on what you want to know.
WebMD called the 800 numbers found on three best-selling water brands, purchased at a minimart in Nashville, Tenn. In each case, we were able to find out the source of the water and the purification process used by the bottler.
But in all three cases we were told that there were no contaminants in the water we were calling about because of the extra purification. While this may be true, water quality experts say it is unlikely that the purification process removes all contaminants. And the Environmental Working Group investigation showed that some of the bottled waters they tested had the same type and level of contaminants as the tap water source used by the bottler.
The brands we checked included Pepsi's Aquafina, Coca-Cola's Dasani, and Deer Park Spring Water, marketed by Nestle.
When we called the Pepsi number, a customer service agent helped us find the date stamp and production code on the bottle of Aquafina we had purchased.
With this information, she was able to tell us that our water came from a municipal source in Mankato, Minn. She further informed us that the bottler used a seven-step purification process that included reverse osmosis, carbon, and UV light filtration.
When we called the Coca-Cola number, a customer service agent was able to tell us that our Dasani came from a municipal source in Birmingham, Ala., and that the purification process included reverse osmosis filtration.
Our Deer Park call was answered by a customer service agent who told us where our spring water was bottled and how it was purified.
Sarah Janssen, PhD, who is a scientist with NRDC, says the 800 numbers may help you figure out where the water you purchase comes from but not what is in it.
"I can't imagine that anyone standing in a store trying to make a decision about which water to buy is really going to go to all that trouble," she says.
Which is safer, bottled or tap water?
Assuming that both the municipal tap water source and the bottler are in compliance with regulations, the experts contacted by WebMD say bottled water is no safer than tap water and tap is no safer than bottled.
The experts point to two cases where bottled water may be recommended -- in emergency situations when contaminants in the local water supply exceed permitted standards and in homes where corroded plumbing could cause lead or copper to contaminate drinking water.
In the first instance, water suppliers are required to notify the community and they may even provide bottled water until the problem has been solved. Homeowners worried about their pipes can have their drinking water tested. Halden says most people choose bottled water for convenience, not safety.
"We have invested in the infrastructure to provide pure, safe, drinking water to the population," he says. "In large cities, water quality is tested hourly, not just once a day."
While that may be true, a recent report by the Associated Press raised new concerns about the purity of tap water.
Its five-month investigation found evidence of a wide range of prescription and over-the-counter drugs -- including antidepressants, antibiotics, anticonvulsants, and sex hormones -- in tested samples of municipal water taken from taps throughout the country.
Twenty-four of the 28 water samples taken from major metropolitan area water supplies contained evidence of drug contamination.
The concentrations of these pharmaceuticals were very small. But the report noted that the EPA has not set safety limits for drugs in water and does not require testing for them.
If I drink tap water, should I use a filter?
If you live in a home with older pipes, have odor or taste issues with your tap water, or just want an extra level of protection, a filter may be a good idea. But you have to get the right one for your specific problem, Janssen says.
"It is important to know what you are trying to filter out before you spend the money," she says. "A reverse osmosis filter will get rid of most contaminants, but charcoal may be enough for odor and taste problems."
The Natural Resources Defense Council web site is a good source for information on filters.
The consumer watchdog group Consumers Union, publisher of Consumer Reports, also weighed in on commercial filters in a report published early last year.
To find out which filter is best for you, the report recommended consulting the Consumer Confidence Report (CCR), published online each July by the EPA.
The report provides detailed information about where your tap water comes from along with detected levels of dozens of regulated contaminants and the corresponding state and federal limits for these contaminants.
To determine the quality of the water actually coming from your faucet, you will have to have it tested. The EPA's Safe Drinking Water Hotline (800-426-4791) can provide the names of state-certified testing labs in your area. Or you can do it yourself for under $20 with a commercially available kit sold at most hardware stores.
Is it safe to drink old bottled water?
The FDA considers bottled water to have an "indefinite safety shelf life" if it is unopened and properly sealed, but drinking water quality expert Rolf Halden, PhD, of Arizona State University is not so sure.
"Even water stored for emergency use should be replaced periodically," he tells WebMD. "You wouldn't want to keep it for 10 years."
Can chemicals leach from plastic bottles and pose a health risk?
Most experts who spoke to WebMD say there is little to worry about.
The major concerns have involved the chemicals bisphenol A and phthalates.
Bisphenol A is used in the production of multiuse polycarbonate water bottles, but not in single-use bottles used by commercial bottlers.
Likewise, phthalates are not typically found in plastic beverage bottles used commercially in the U.S. But Janssen says phthalates have been found in bottled water, suggesting that it may leach from the plastic cap or liner.
"These chemicals may be in your water, but you would never know because the water companies are not required to test for them," she says.
Is freezing bottled water or leaving it in a hot car dangerous?
Both of these concerns have circulated widely in emails and on the Internet. One email that has been around for several years warns that freezing bottled water leads to contamination with carcinogenic dioxins.
The email was erroneously attributed to Johns Hopkins University, and it was so widespread that Johns Hopkins' scientists felt compelled to publicly set the record straight in a news release.
Rolf Halden, PhD, PE, who is an adjunct associate professor with the Johns Hopkins Center for Water and Health, called the claim "urban legend."
He notes that there are no dioxins in plastics and that freezing actually slows or prevents the release of chemicals.
The industry group representing single-use beverage bottle manufacturers, known as NAPCOR also used the term "urban legend" to describe claims that it is unsafe to drink water that has been left in a hot car.
"The idea that (these) bottles 'leach' chemicals when heated in hot cars is not based on any science, and is unsubstantiated by any credible evidence," the group noted in a recent news release. "This allegation has been perpetuated by emails until it has become an urban legend, but it just isn't so."
Is there fluoride in bottled water?
If it is added by the bottler, the label must say so. But most bottled waters probably don't have as much fluoride as fluoridated tap water.
The CDC has stated that most bottled waters contain fluoride at levels that are less than optimal for oral health. It weighed in on the issue in a news release last February.
"If you mainly drink bottled water with no or low fluoride and you are not getting enough fluoride from other sources, you may get more cavities than you would if fluoridated tap water were your main water source," the statement noted.