They can be used to reduce both large and small particles, depending upon the density of the filter. Pleated filters are fabricated from polypropylene, paper, or glass fibers. They consist of a sheet of porous material that has been pleated around a central core. The more material used, the more particulate matter that can be retained before the filter plugs. The pore sizes determine the coarseness of particles that are trapped by the filter.
Ceramic filters have a raw pottery appearance.
Chemical Adsorptive Filters Chemical adsorptive media filters reduce dissolved impurities through a chemical adsorptive process. Their capacity depends on the amount and type of media and the flow characteristics of the filter. For some impurities, reappearance of bad tastes and odors indicates that filter capacity has been reached. For health-related impurities, careful monitoring of usage is needed to determine when capacity has been reached. Granular activated carbon media filters consist of medium mesh-sized carbon from a coal, wood, or coconut shell source.