Safe Drinking Water
(Page 4 of 6)
June/July 2003
By Lynn Keiley
Though their price and versatility may be appealing, carbon filters need to be changed regularly or they can actually become a source of contaminants. Bacteria feed on organic matter that accumulates on the surface of the carbon. If the filters aren't changed regularly, these bacteria can make their way into the water supply.
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Both carafes and faucet-mounted carbon filters can be somewhat slow to actually get their filtration jobs done, especially as the filter nears the end of its useful life.
POINT-OF-ENTRY FILTERS
Sometimes called sediment filters, these units are plumbed into the system where water service enters the house. These filters usually trap large particles of sand, dirt or mineral contaminants and treat all of the water used in the house. Prices range from about $50 to $200.
POINT-OF-USE FILTERS
Countertop/Faucet. These filtering units are mounted on or below the counter and are connected to the faucet through tubing. A valve diverts water into the unit when you want to filter water. Most units reduce chlorine byproducts, lead and parasites; the better models also will remove chemical contaminants and certain pesticides. Expect to pay about $120 to $140 for one of these units. You may need a plumber to help install it.
Reverse-osmosis filters are considered by many to be the most sophisticated homewater treatment option. "Reverse osmosis filters remove the broadest spectrum of chemicals from water as well as give the highest removal rates," says the EPA's Daughton. Reverse osmosis filters reduce a wide range of contaminants including chlorine byproducts, many pesticides, lead, nitrates, bacteria and other microorganisms. (Parents should be aware that many of these filters also remove fluoride.) The process involves forcing water through very fine membranes small enough to trap molecules of pollutants, but large enough to allow the water to pass. It's a slow process that produces just a few gallons of water at a time, which are typically stored in tanks below the sink.
Is Bottled Better?
There's no denying that bottled water can be convenient when you're on the go, and it's certainly a healthier option than most soft drinks. But if you're buying bottled water because you think you're getting better quality for your money, you may be disappointed. Many brands of bottled water are nothing more than filtered municipal water, hailing from cities such as Houston, Orlando, Fla., and Fresno, Calif. Bottled water, considered a food, is regulated by the U.S. Food and Drug Administration. Tests conducted by the Natural Resources Defense Council found that while most bottled waters are of good quality, about a quarter of the bottles tested contained levels of bacteria and chemicals that exceeded levels allowed by the state of California (which in some cases has more stringent regulations than the EPA). Considering that bottled water can cost up to 1,000 times more than tap water, that's not much of a bargain.
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