When negatively charged contaminants contact the resin, iodine is instantly released killing the microorganism. By this process, organisms are killed, without large amounts of iodine actually being in solution. In addition, as a final step, many filters are granulated activated carbon to remove organic pollutants, radioactive particles, pesticides and other chemicals, including halogens used in the filter. This greatly decreases objectionable color, taste, and odors. Many filters require periodic cleaning to remove trapped matter and organisms.
Clogged pores require increased water pressure which can damage filters.
The cleaning process can cause damage. It is difficult to recognize when filters are damaged and are no longer functioning effectively. The relationship between pore size vs. organism is misleading.