As with most filtration methods, water is introduced to one side of the filter, which acts to block the passage of anything larger than a water molecule. Only water and smaller contaminants will pass through to the other "clean" side of the filter. Additionally many ceramic water filters (CWF) are treated with colloidal silver to further incapacitate bacteria and prevent the growth of mold and algae in the body of the filter. The two most common types of CWF are pot type and candle type filters. CWF systems consist of a porous ceramic filter that sits on top of a plastic or ceramic receptacle. Contaminated water is poured in the filter and passes through the filter into the receptacle below. The receptacle usually is fitted with a tap. Contaminants which are larger than the minute holes of the ceramic structure will remain in the top half of the unit, which can be cleaned by brushing the inside of the top section with a soft brush and rinsing it out. Hot water and soap can also be used. Some ceramic filters (like ceramic candle filters) also use active carbon which absorbs compounds such as chlorine. Filters with active carbon need to be replaced periodically because the carbon becomes clogged with foreign material.
There are also portable ceramic filters, such as the MSR Miniworks, which work via manual pumping, and in-line ceramic filters, which filters drinking water that comes through household plumbing. Cleaning these filters is the same as with the clay pot filter but also allows for reverse-flow cleaning, wherein clean water is forced through the filter backwards, pushing any contaminants out of the ceramic pores.
This filtration type does not remove chemical contaminants. Silver-impregnated media in some filters may cause other by-products which are chronically harmful to human health. The major risks to the success of all forms of ceramic filtration are hairline cracks and cross-contamination. If the unit is dropped or otherwise abused, the brittle nature of ceramic materials can allow fine, hard to see cracks can allow larger contaminants through the filter. Also, if the "clean" water side of the ceramic membrane is brought into contact with dirty water, hands, cleaning cloths, etc, then the filtration will be ineffective. If such contact occurs, the clean side of the filter should be thoroughly sterilized before reuse.
Several NGOs are supporting the expansion of the use of ceramic filters in drinking water development initiatives; most commonly, in the form of clay pot filters. Ron Rivera was a key proponent and innovator in the field.