Ceramic filters are made from porous ceramic material with the micron rating and quality dependent upon the manufacturer. Ceramic filters are either hollow in the middle as is the case with ceramic sediment filters or contain carbon as is the case with single filter systems.
The ceramic outer case or shell of the cartridge is usually 5-8 mm thick and made from a similar material to floor and wall tiles except they are porous and have larger pore sizes allowing the water to pass through while trapping contaminants as small as 0.3 microns in size.
The micron rating of the filters generally varies from 0.3 to 5 micron with 1 micron the most common. Water travels/moves from the outside of the filter to the inside trapping contaminants on the outside. Due to the filter depth (5-8 mm) they also trap different shaped particles and provide an overall higher quality filtration than pleated cartridges or wrapped carbon cartridges. They can also be cleaned returning their performance to that of a near new cartridge and giving them a long usage life. They are however susceptible to breakage or cracking if dropped or knocked hard.
Of all the manufacturers, Doulton is considered the world leader for this type of filter. Their ceramic filters are rated at 0.9 microns absolute or 0.3 micron nominal meaning they will reduce/remove cysts such as cryptosporidium by 99.999% and bacteria by 99.99%. These filters are NSF certified and can be cleaned over and over again with a “scotchbrite” pad without affecting the performance.
Ceramic filters tend to be more expensive, but they last for years and generally have a higher quality of filtration increasing their popularity over the last few years.