Understanding NSF Standards:

Filter Certification is for each contaminant under the applicable Standard.  For example, a filter tested under Standard 42 for chlorine is not necessarily tested for chloramine.

Standard 42 (aesthetics) applies to these contaminants:  Chlorine, Chloramine, Bad Tastes &  Odors, Sediment.
How much Sediment / Particulate is reduced under Standard 42 is noted by "Class"
Class I Particulate reduction: to ½ - 1 micron;
Class II: 1 to < 5 microns;
Class III: 5 to <15 microns;
Class IV: 15 to < 30 microns;
Class V: 30 to < 50 microns;
Class VI: > 50 microns.
One Micron = 39 millionths of an inch. (Cysts are 3-7 microns, so Class I filters will remove cysts)

Standard 53 (health effects) for the reduction of specific health-related contaminants, such as cysts (Cryptosporidium, Giardia, Entamoeba, and Toxoplasma), lead, volatile organic chemicals (VOCs)* including THMs (TTHMs), organics, tannins. and MTBE (methyl tertiary-butyl ether), that may be present in public or private drinking water.

* Products certified for reduction of VOCs under Standard 53 will be effective for all of the following contaminants, many of which can be categorized as Pesticides, Herbicides, or Insecticides.

simazine
styrene
1,1,2,2-tetrachloroethane
tetrachloroethylene
toluene
2,4,5-TP(silvex)
tribromoacetic acid
1,2,4-trichlorobenzene
1,1,1-trichloroethane
1,1,2-trichloroethane
trichloroethylene
trihalomethanes (TTHM) **bromodichloromethane
**bromoform
**chlorodibromomethane
**chloroform
xylenes

The NSF (National Sanitation Foundation) and Water Quality Association set Standards and testing protocol.  To have filters tested by the NSF is quite costly.  Therefore, 3rd party laboratories sometimes do the testing according to the NSF protocols.  Also, sometimes a company like Selecto will have some of their filters tested by the NSF and others tested by a less costly third party laboratory to validate their own tests, especially since the filter housing, components, and filtration media are identical to the NSF certified  filters - the only change being size and volume.  They may also have the NSF test for some contaminants, and a third party laboratory test for other contaminants. This is why one filter may be listed on the NSF site, and another is not.  Or why some contaminants are listed on the NSF website and others not.  For complete data on testing for each filter, click on the picture of that filter to view the cut sheet.

If you want to learn more, go to NSF.org.

You may want to check to see if any filter you are considering is listed HERE.

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