Easy water filtering: how to choose an optimal system.

While it may be Earth's most precious resource, water certainly isn't treated as such. Americas drinking water is often exposed to chemical additives, sewage, pesticides, herbicides and sometimes toxic waste, leaving many consumers distrustful of the agencies that regulate it.

A study conducted by the Natural Resources Defense Council (NRDC) reports that pollution, old pipes and outdated treatment facilities played a part in reducing the quality of drinking water in 19 U.S. cities. Some water supplies have been tainted by lead, pathogens and even perchlorate (which doubles as rocket fuel).

Fortunately, it has never been easier to enjoy your tap water without ever having to purchase expensive, wasteful, and possibly dirtier, bottled water (see "Message in a Bottle," September/October 2003). Water filters can be highly effective in removing contaminants, and many cost pennies a day to operate.

"Before deciding on a filtration system, it's best to find out what's actually in your water," suggests Tom Round, vice president of Silver Lake Research Corporation. Your city's right-to-know report (also called the consumer confidence report) examines your drinking water and anything else lurking in it. These reports, however, can be difficult to decipher.

Consumers can advocate for cleaner water, as well as take matters in their own hands. Home testing kits from companies such as Silver Lake ($16.99) allow you to check your water for the most prevalent contaminants and compare it with standards.

"Water is constantly changing;' explains Round. "By the time the right-to-know report comes out, your drinking water could be entirely different."

Array of Choices

While there may be a plethora of choices on the market, filters certified by the independent National Sanitation Foundation ensure manufacturers are living up to their claims.

Pour-through carafes are the most popular way for consumers to filter their water in small batches. As water flows through the carafe, activated carbon in the filter clings certain contaminants to its surface, while an ion exchange resin binds heavy metals.

The Pur Advantage CR-1500R ($18) received Consumer Reports' (CR) highest overall score for carafes, testing high for flow rate and the ability to remove chloroform, lead and off-tastes. This model conies equipped with a life indicator, thus eliminating the guesswork of when to replace the filter. It is also certified to remove both mercury and atrazine. The Brita Classic ($20) also obtained a "very good" rating from CR.

Faucet-mounted units are available to provide filtered water on demand. The GE SmartWater ($22) received a "very good" score from CR and is designed to remove sediments and cysts. Faucet-mount designs give you the option to bypass the filter when it isn't needed, thus prolonging its life. However, the filters should be replaced every three months to ensure peak performance. Leading the industry in sustainability is Terraflo, which offers customers the ability to mail back used filters for recycling free of charge, thereby preventing the collected toxins from re-entering the environment.

Undersink systems such as the Kenmore 38460 ($80) have filters that can last twice as long as carafe or faucet-mounted units. However, the filters in these models can be difficult to change, and professional installation might be required.

Reverse-osmosis models work by sending water through a pressurized membrane. The unit strains molecules too large to pass through it, blocking most contaminants. Unfortunately, these units waste five gallons for every gallon purified. Also, be ready to wait up to 50 minutes to enjoy a half-gallon of water.

To shield your entire home from contaminants, whole-house filtration systems attached to your water main might be a wise choice (around $1,000). Typical models are certified to remove a spectrum of contaminants. Most require professional installation.

For that extra feeling of clean, shower filters are also available and sporting some high-tech features. Rainshow'r offers a filter ($41) with a "see-through" window, showcasing the sediment it traps. It's also equipped with a valve capable of turning your water off during wasteful periods of shampoo lathering.

Touted by some as water's purest form, distilled water is produced by condensing steam from boiled water back into its liquid state. The common belief that distilled water can leach minerals from your body due to its pureness is debatable. The American Medical Association concludes there is no evidence of "any adverse health effects from the continued ingestion of distilled water:'

While proven highly effective in removing microorganisms, distillers are unable to remove volatile organic compounds having boiling points lower than water. They also can be water and energy intensive and can take hours to purify. Waterwise makes a model ($389) that combines a distiller with a carbon filter. CONTACT: Consumer Reports, www.consumerreports.com; Rainshow'r and Terraflo products available at http:// emagazine.greenhome.com/products; Silver Lake Research Corporation, [phone], www.watersafetesttdts.com.

FRED DURSO, JR. uses a carafe to purify his New Jersey tap water.