We have been using those screw-on tap filters for couple of years, and are considering moving to an under-the-counter water filtration system, so before putting out the big bucks, I figured some research was in order.
Before purchasing anything, it is fundamentally important to know what the local water contaminants are that the system must filter out, so that one does not overspend to remove something that is not in the water supply, and miss filtering out something important that is there. You can get your water tested through www.aquamd.com, and they will help direct you towards the filter that will best deal with your water.
In my Vancouver water supply, ozone is the primary method of water treatment, destroying the water-born micro-organisms. Chlorine is the secondary method of disinfection used in the distribution system, which means also Trihalomethanes (THMs) and Haloacetic Acids (HAAs), two carcogenic biproducts of water chlorination are in the water supply. Thankfully our water is not fluoridated. Lead from pipes in homes that were built prior to 1989 would need to be filtered out also. Well water out in the Vancouver Lower Mainland valley is frequently contaminated with arsenic, so get your water tested and choose your filter appropriately.
My primary concern will be to filter out the chlorine and its biproducts, the THMs and HAAs, which are poisons that not only kill our vital gut bacteria impairing our digestion and immune system, but are also linked to cancer (particularly bladder cancer) when consumed, inhaled, or absorbed through the skin. For this reason, whole-house filtration systems are best, as then bath water and shower water will be chlorine-free too. As they say, if it is on your skin, you are drinking it! The cheapest way to eliminate chlorine from water is to let it sit, but possibly you may be inhaling the chlorine instead.
There are many kinds of filters out there, so what to choose? Make sure any filter you select is certified by either NSF International, CSA International or Underwriter's Laboratories. Here are the advantages and disadvantages of various systems:
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Related Tips
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Bacteria, the soil, the gut and detoxification
Villanueva CM et al. Meta-analysis of studies on individual consumption of chlorinated drinking water and bladder cancer. J Epidemiol Community Health. 2003 Mar;57(3):166-73.
Villanueva CM et al. Bladder cancer and exposure to water disinfection by-products through ingestion, bathing, showering, and swimming in pools.
Am J Epidemiol. 2007 Jan 15;165(2):148-56. Epub 2006 Nov 1.
Zwiener C et al. Drowning in disinfection byproducts? Assessing swimming pool water. Environ Sci Technol. 2007 Jan 15;41(2):363-72.
Chevrier C et al. Does ozonation of drinking water reduce the risk of bladder cancer? Epidemiology. 2004 Sep;15(5):605-14.
Online at CBC Marketplace Shopping for home water filter systems
Online at Metro Vancouver Water treatment process
Online at Water treatment guide
Online at NSF
Online at How Stuff Works - Activated carbon filtration
Online at Reverse Osmosis
Online a Natural Resources Defense Council
Online at Fine Waters
Copyright 2007/2010 Vreni Gurd
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