This WaterSentinel refrigerator water filter contains a compressed carbon block which provides tremendous capacity to remove and/or reduce impurities and sediment that may be present in your drinking water. The carbon block has millions of active sites on its surface and within the structure which can absorb impurities like a sponge, and can adsorb and hold other types of impurities on its surface like a magnet. Additionally, this filter can catalytically breakdown other impurities very similar to the way a catalytic converter works in your automobile. These processes ensure that you are getting the cleanest and best tasting water possible. This filter has been tested by the manufacturer against ANSI/NSF Standard 42 for the reduction of Chlorine, Tastes and Odors.