In 2007, Americans consumed more than 9 billion gallons of bottled water, averaging more than 30 gallons per person.

Why do so many thirsty people choose to drink bottled water instead of tap water? While some prefer the taste and convenience of bottled water, others believe that bottled water is safer to drink. Is this true?

For healthy people, both bottled water and tap water are considered safe to drink if they meet the standards of the US Food and Drug Administration (FDA) and Environmental Protection Agency (EPA). The FDA sets food safety, labeling, and inspection standards for bottled water, and the EPA sets standards and conducts frequent testing for municipal drinking water. But the sources and treatments of drinking water can vary considerably.

Evidence for the Health Claim

The taste and quality of drinking water depend on where it comes from and how it is chemically treated. Most tap water comes from surface sources, such as rivers, lakes and reservoirs. Most bottled water comes from ground sources, such as underground aquifers.

The taste and quality of ground water are less likely to vary day-to-day than water from surface sources. And water deep underground is less vulnerable to contamination than water on the surface. Even so, ground water can contain high levels of contaminants or be contaminated during the bottling and/or treatment processes.

How do you know where your water comes from? If your tap water’s source is a public water system, you can check your annual water quality report or contact your water supplier to find its source. For bottled water, you can read the label to find out where the water comes from:

• Artesian water, ground water, spring water and well water: come from underground aquifers
• Distilled water: steam from boiled water that is recondensed and bottled
• Mineral water: ground water that naturally contains dissolved solvents such as minerals, salts, and gases
• Purified or sterilized water: may originate from any source, but is supposed to be treated according to the US Pharmacopeia (USP) standards for purification and sterilization, respectively

If you are still unsure of where your bottled water comes from or how it is treated after reading the label, call the manufacturer for more information.

In certain circumstances, tap water may become contaminated by substances such as disease-causing germs, making it unsafe to drink. In these instances, your water supplier is required to notify you by mail, radio, television or hand-delivery that your water does not meet safety standards. The notice you receive will describe precautions you need to take (e.g., boiling your water).

Drinking water may also become contaminated with toxic metals, including arsenic, barium, chromium, lead, mercury and silver. These metals may enter the water supply from natural sources, industrial processes, and materials used in plumbing systems. Since exposure to toxic metals can have serious health consequences, most water systems are tested regularly to make sure the levels of these substances are within safe standards.

If you are concerned about contaminants in your home’s drinking water, have it tested. For more information about testing your water, contact the Environmental Protection Agency’s Safe Drinking Water Hotline at 1-800-426-4791.

Evidence Against the Health Claim

Although bottled water is considerably more expensive than tap water, it is not necessarily safer. In fact, all drinking water, both bottled and tap, may contain small amounts of contaminants. Furthermore, unlike publicly supplied tap water, the purity of bottled water is not regulated by the government.

A study that was published by the National Resources Defense Council tested more than 1,000 bottles of 103 brands of bottled water. The researchers found that while most of the bottled water tested was of high quality, about 1/3 of the water contained levels of contamination that exceeded state or industry standards or guidelines.

Additionally, tap water typically contains fluoride, which promotes strong teeth and prevents tooth decay, which bottled water usually does not have. Also, there have been some reports that say that one of the chemicals that plastic bottles are composed of (bisphenol-A [BPA]) can leach into water when exposed to high temperatures. BPA has been associated with impairment of the reproductive organs and have adverse effects on breast tissue and prostate development.

Conclusion

If you  are interested in finding out about the source and quality of your public water supply, you can read your local water supplier’s annual water report or call and request a copy. If your water comes from a private well, make sure that the water is tested annually for nitrate and bacteria, and more frequently for other contaminants if you suspect a problem. And you can contact the manufacturer of your bottled water to request the results from the latest testing and find out how the water is treated to remove contaminants.

Once you are satisfied the water is of acceptable quality, consider its taste and expense. If a designer bottle of water tastes better to you and fits your budget, by all means, drink up. But if you are looking to save money, most publicly supplied tap water in the US is safe to drink and tastes just fine.