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Bottled Water — Health Or Hype?

A consumer's guide to smart thirst-quenching

By Nneka Leiba, M.Phil., MPH


Filtering Your Tap Water

Filtered tap water.

There are many systems available to improve the quality of tap water, whether you are filtering just one glassful or all the water coming into your house. Before you choose one, it's important to clarify your objective, which might be to find a basic filter at a good price, or maybe to remove as many contaminants as possible. The decision is easier to make if you know what's actually in your tap water. To find out, ask your local water utility to send you a copy of their Consumer Confidence Report, which contains testing information for your water supply. Private wells should be tested regularly.

Once you know what you need to remove, you can choose from among the various filtration technologies, including:

Carbon/Activated Carbon: Carbon chemically bonds with and removes some contaminants in water filtered through it. Carbon filters vary greatly in effectiveness: some just remove chlorine and improve taste and odor, while others remove a wide range of contaminants including asbestos, lead, mercury and volatile organic compounds (VOCs). However, activated carbon cannot effectively remove other common inorganic pollutants such as arsenic, hexavalent chromium, nitrate and perchlorate.

Reverse Osmosis: This process relies on a semi-permeable membrane that retains particles larger than water molecules. Reverse osmosis can remove many contaminants not removed by carbon, including arsenic, hexavalent chromium, nitrates and perchlorate. Quality varies, both in terms of the membrane system itself and the carbon filter typically used with it. The filters use 3 times to 20 times more water than they produce, so they are usually used only for drinking and cooking water.

De-ionization: An ion (electrically charged particle) exchange process removes mineral salts and other ions from water. The process cannot remove non-ionic contaminants (including disinfection byproducts and other common VOCs) or microorganisms.

Ion Exchange: This technology passes water over a resin that replaces undesirable ions with others that are more desirable. One common application is water softening, replacing calcium and magnesium with sodium. The resin must be periodically “recharged” with replacement ions.

Water Softeners: These devices use ion exchange to lower levels of calcium and magnesium (which can build up in plumbing and fixtures) as well as barium and certain forms of radium. They do not remove most other contaminants. Since water softeners usually replace calcium and magnesium with sodium, treated water typically has a high sodium content, which people with certain health conditions may need to avoid. Softened water is not recommended for plants and gardens for the same reason.

UV (ultraviolet): These systems use ultraviolet light to kill bacteria and other microorganisms. They cannot remove chemical contaminants.

For more information on choosing a filter, go to

The Quest For Purity: A Brief History Of Water Treatment

Water treatment was recently designated one of the most significant public health advances of the 20th Century by the Centers for Disease Control and Prevention. It's no wonder: Purification of drinking water has prevented the spread of deadly waterborne diseases and saved untold lives.

Water purification.

Yet as far as we've come in our efforts to purify our drinking water, some basic methods used today are virtually the same as they were hundreds, even thousands, of years ago. Ancient Sanskrit and Greek writings yield evidence of water being improved by filtration through charcoal, exposure to sunlight, boiling, and straining — as far back as 4000 B.C. The Egyptians reportedly used the chemical alum around 1500 B.C. to cause particles suspended in water to settle out. This is still done in some water treatment systems.

For centuries, the goal of water purification was to eliminate impurities that could be seen, smelled or tasted. It wasn't until the 1800's that the dangers of what couldn't be perceived with the senses became a more urgent concern. In 1855, epidemiologist John Snow linked a cholera outbreak in London to a sewage-contaminated public well, kicking the quest for water purity into high gear.

Because disease-causing microbes were discovered in suspended particles including fecal matter, early water treatment systems in Europe and the United States were designed to clarify water by filtering it though sand. Though filtration did indeed reduce the cloudiness of drinking water and is still an important step in the process of modern water treatment, disinfectants such as chlorine (first used to disinfect Jersey City water supplies in 1908) played the greatest role in reducing waterborne disease outbreaks. Chlorine is still widely used in public water systems, along with ozone and chloramines.

By the late 1960's, a new health concern came to the forefront: water contamination from the runoff of chemicals used in agriculture and industry. In 1974, Congress passed the Safe Drinking Water Act, which was strengthened in 1986 and again in 1996. The act requires the U.S. Environmental Protection Agency to set legally enforceable water quality standards and treatment requirements for the nation's 170,000-plus public water systems, and, aided by the states, to protect this valuable natural resource from source to tap.

Playing It Safe

For health and environmental reasons, EWG recommends that you drink filtered tap water.

For health and environmental reasons, EWG recommends that you drink filtered tap water. You'll save money, drink water that's purer than unfiltered tap water and help solve the global glut of plastic bottles. Carry it with you in a stainless steel bottle to eliminate the potential health risk from plastic containing BPA.

When buying bottled water is unavoidable (and it's always better to stay hydrated than to do without — or to drink cavity-causing soda), use EWG's Bottled Water Scorecard to find brands that disclose the water's source location, treatment, and quality, and that use advanced treatment methods to remove a broad range of pollutants. You can find these brands on our website (, along with information on different municipal systems' water quality reports and how to select an appropriate filter for your tap.

Above all, take the claims of bottled water companies with a grain of salt. Pricey does not necessarily mean healthy; that pure mountain spring may exist only on the label.