Although the exact composition may vary, ceramic filters are generally made from a fine silica powder originally formed from the cell walls of microscopic algae deposited in lake beds millions of years ago. This prehistoric sediment is known as diatomaceous earth (or kieselguhr). Today there are over 1500 uses of this material, including as a polishing agent in nail polish and as an insulator in kilns. The diatomaceous silica is fired at high-temperatures into a filter cartridge or candle.
Ceramic filters work by simply allowing the water to seep through tens of millions of pores in the cartridge surface. In the process, organic and inorganic particulates too large to pass through (often anything larger than 0.5 micron) accumulate on the ceramic surface. As a point of reference, even cysts (like Cryptosporidium and Giardia) are too big in size to squeeze through the tiny pores of the ceramic filter cartridge.
Contaminants that may pass through the outer surface of the filter cartridge are likely to be intercepted within the ceramic depth. Here inside the ceramic filter, even much smaller particles can be captured. This is because any remaining particulates in the water have to navigate through an intricate maze. This labyrinth of twists and turns involves so many sharp angles that contaminants that may have penetrated the topmost layer become trapped within the underlying complicated structure of the ceramic.
Many ceramic filters also incorporate a silver compound into the ceramic itself, because it acts as a bacteriostatic agent to repel bacterial growth in and on the filter. A granular activated carbon core may also be added to the ceramic core to reduce chlorine and other undesirable taste & odor issues–as well as pesticides, THMs and VOCs.
Ceramic filters have the distinct advantage of having the capability to be reused several times before needing replacement. In order to function effectively, however, their surface area must be regularly cleaned. Otherwise, the outer surface could become so clogged with contaminants that water will no longer pass freely through the cartridge.
Ceramic filter products are available for use at home and away from home. In the house, ceramic filters can be located under the sink or on the countertop, as well as in 10″ big blue housings. Away from home, ceramic filtration offers the additional advantage of using a gravity-fed filter system, which doesn’t require electrical power or manual pumping to function. This can be an ideal choice in wilderness or emergency situations, when clean, safe water is scarce and electricity is unavailable.