Granular Activated Carbon is probably the most well known of all filter media. It is designed to remove a long list of organic pollutants. These include herbicides, pesticides, insecticides, volatile organic compounds (VOCs), chlorine, taste and odor. It can either be in a granular form (like sand) or block (like brick). When the carbon is compressed into brick, the filter can have a certain micron rating for particulate removal. These ratings can range anywhere from 50 microns down to 0.1 micron. The most common rating is 5 microns. The two (2) most popular sources are made from bituminous coal or coconut shells. The carbon has different size pores that physically “adsorb” or “trap” organic contaminants. Depending on the quality of the water source, the filter will have a specific life span, then, it is necessary to change the filter.