A nominal 5 micron water filter can trap 85 percent of particles of five microns and larger in water as it flows through the filter, whereas an absolute 5 micron water filter traps 99.9 percent of particles larger then 5 microns. For most purposes nominal aqua filtration is fine but for high quality water purification an absolute-rated water filter is best for the job.

Sediment filters do just that, they are designed to filter out particles like rust, silt, sand, dirt, clay, and decomposing organic material from water. Sediment water filters do not normally remove chemical contaminants unless they are a combination system or a dual filter.

Ceramic aqua filters are very tight aqua filters whose absolute filtration rating is too tight to allow the passage of, cysts, bacteria or pathogens like cryptosporidium or giardia. Ceramic water filter cartridges purify water by straining out pathogens but they do not remove chemicals (unless accompanied by an additive, like carbon, that does).