Protozoan cysts (i.e., Cryptosporidium parvum oocysts) in the water supply caused a number of deaths in Milwaukee, Wisconsin in 1993. As a result, many people are quite concerned about removing cysts from their water. This has resulted in ceramic filters becoming more and more common in the U.S.
What is a Ceramic Filter?
While the precise composition of various ceramic filters may vary, they’re generally are made of a high-temperature-fired type of diatomaceous earth (DE). DE is a fine silica powder made up of the cell walls of microscopic algae. It seems that the specific filtering ability of a ceramic filter depends on it’s pore size, and pore size is primarily determined by the ceramic base material used and the temperature at which it was kiln fired.
How do Ceramic Filters Work?
Very simply. Water just seeps through the tens of millions of pores in the ceramic material, which is usually in a cartridge form. In this process, solids (such as many kinds of sediment and organisms) accumulate on the ceramic surface — if they’re too large to pass through. For your information, most (some filters claim as high as 99.9%) of Cryptosporidium parvum oocysts are caught through this process.
You should be aware that sometimes a silver compound is incorporated into the ceramic itself to act as a bacteriostatic agent (to counter bacterial growth on, or in, the filter). These filters are manufactured in such a manner that the silver cannot migrate into the finished filtered water. However, the U.S Federal Trade Commission (FTC) reported that filters with bacteriostatic additives “have shown unpromising results.” In other words, silver does not meet the FTC’s anti-bacterial expectations of effectiveness.
Today, ceramic filters can be purchased as stand-alone, counter-top, gravity-feed models (no added water pressure is required to make the water pass through the filter) or combined with activated charcoal in some type of filtering cartridge. Often, manufacturers will suggest periodically washing the ceramic off. Depending on the kind of cartridge, it may last 6-12 months. (Read manufacturer’s product literature to be certain.)
The Downside
Drawbacks include the fact that volatile organic chemicals (VOCs), chlorine and other undesirable odor and taste compounds, will remain in the treated water after ceramic filtering. (Of course, ceramic filters can be combined with other filtering strategies.) Also, regular filter cleaning must be performed. If forgotten, or considered an unnecessary chore, the outer ceramic surface could become so clogged with contaminants that water no longer freely passes through the filter.
From Creating a Healthy Household: The Ultimate Guide For Healthier, Safer, Less-Toxic Living, © 2000 by Lynn Marie Bower. Used by permission.
