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The Honolulu Advertiser
Posted on: Thursday, September 27, 2007

Some pros and cons of using water filters

By Laurie Steelsmith

Hawaii news photo - The Honolulu Advertiser

Some water filtering systems can be attached to a sink faucet, like this one by Pur, while others are countertop units or stored under the sink.

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Q. Do I need to use a water filter on my faucet? And if so, what kind should I buy? Please explain which types are available.

A. There is some controversy on the subject of whether or not you need a water filter. I recommend that my patients purchase one for health reasons, and also because it can result in better tasting water.

In Hawai'i, we are blessed to have water that is exceptionally clean at the source. By the time it reaches your faucet, however, chlorine has been added (only in some areas on O'ahu), as well as potential contaminants from the pipes that it runs through. The chlorine, which is added to kill bacteria, can pose a health risk if it reacts with organic matter such as soil, fertilizer or plant materials.

According to the Environmental Working Group, "a compelling body of scientific evidence — nearly 30 peer-reviewed epidemiological studies — links chlorinated by-products to increased risks of cancer."

Here are three of the most common types of water filters that you are likely to find on the market, and a few of their pros and cons:

  • Activated carbon filters are granulated carbon filters that remove chlorine, parasites, viruses and organic chemicals from your water. Unfortunately, they have two downsides: first, they are not the best when it comes to removing heavy metals and all micro-organisms. Second, bacteria collected by these filters can actually be dumped back into the water that you've filtered. I generally don't recommend this type of filter.

  • Solid carbon block filters are better than activated carbon filters because they are less likely to allow bacteria to thrive in their filtering systems. They trap everything that activated carbon filters do, while also trapping more organic pollutants and chemicals. However, it is important to change the filters twice a year, or when they are no longer able to filter water efficiently.

  • Reverse osmosis filters are the most effective for purifying your water, because they have three filtering mechanisms: a sedimentation filter, a reverse osmosis filter and a carbon filter. These systems remove everything that solid carbon block filters do, along with 100 percent of the organic material, but they remove all beneficial minerals as well. Reverse osmosis filters are energy efficient but not water efficient; they can waste about two to three gallons of water a day. They may require a plumber to install, and their filtering membranes should be replaced every year.

    Some water filtering systems are countertop units, while others can be stored under your sink. Many types of filtering systems can be attached to your sink faucet.

    Laurie Steelsmith is a naturopathic physician and licensed acupuncturist in Honolulu, as well as author of the new book, "Natural Choices for Women's Health," published by Random House. You can reach her and read her past columns at www.DrSteelsmith.com. This column is for information only. Consult your health provider for medical advice.