By: DLangford
Water filter comparison and choice is greatly simplified by the system of certification used for home water filters. One of the criteria for choosing a filter should be whether or not it is certified by one of the three accredited testing organizations: The National Sanitation Foundation International (NSF), The Underwriters Laboratories (UL), or The Water Quality Association (WQA).
What Does It Mean to Meet a Standard?
Suppose a filter has the NSF seal of approval for Standard 53. What does this mean? Does it mean they have met all the standards set for each contaminant tested under Standard 53? No! You always need to ask, "For what contaminant or contaminants have they met Standard 53?"
A manufacturer claims that their filter can remove a list of specific contaminants. NSF is a neutral third party which uses rigorous standards and methods for testing that filter to see if it really does remove those specific impurities. For the impurities that pass the reduction test, it issues its NSF "seal of approval" saying, "This filter effectively reduces these contaminants."
If they have met the reduction standard for lead, for example, that means they have the "seal of approval" for reducing lead to an acceptable level. You can see that one filter might effectively reduce one health-related contaminant and another effectively reduces 15 health-related contaminants and both get to claim NSF seal of approval for Standard 53. So look closely at what has been tested and verified.
What does the Term Reduced Mean?
A second question that needs clarification is what does the term "reduced" mean? When NSF says a filter "reduces" lead in the water, what does that mean? Is it reduced to a specific level or is it "reduced" in a relative sense meaning "lowered the amount of"?
Let me try to clarify. The Environmental Protection Agency (EPA) has set two standards for each contaminant. One is called the MCL or the Maximum Contaminant Levels and the other is the MCLG or the Maximum Contaminant Levels Goal. The first is what is required of public water utilities and the second is the ideal level they should be aiming at. The public water utility is required to inform the public on each contaminant and if they don't reach the MCL for a contaminant they must point it out to the public in their annual water quality report.
It is this former standard, the MCL or Maximum Contaminant Levels standard that NSF International is testing water filters against for filter certification. They introduce high levels of that contaminant into the water and then test the filter to see if it reduces that contaminant to the MCL of that impurity. If the filter claims to work for 500 gallons before changing it, they run all 500 gallons, testing periodically to be sure that contaminant is reduced to the MCL level continuously up till the last of the 500 gallons.
All this is done for your benefit so you can be sure that the filter you are buying is effectively reducing the contaminants they claim to be reducing.
A Useful Tool
NSF has a useful tool on their website for verifying whether or not a given filter is certified. This tool is entitled "Product and Service Listings" and can be found at http://www.nsf.org/Certified/dwtu/. It will tell you the number of the standard for which the filter is certified and exactly for which contaminants it is certified to reduce.
For a more complete explanation of water filter comparison and certification as well as other criteria to use in choosing a water filter, check the free report cited below.
About the Author
David G. Langford http://www.all-about-water-filters.com To get a free report entitled "A to Z Checklist, How to Choose a Water Filter?" go to http://www.atozwaterfilterguide.weebly.com
Article Directory Source: http://www.articlerich.com/profile/DLangford/72426
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