Drinking Water Filters
The most common type of drinking water filters are the particle filters. These filters use a porous material, similar to a membrane, to trap unwanted particles. The smaller the holes in the filter, the smaller the particles it can trap. Filters are measured according to the size of these holes, with a measurement unit called a micron. The lower the micron rating, the more effective that filter will be. For example, while a filter that removes particles down to 5 microns in size produces clean water, one that stops particles 0.5 microns in size produces cleaner water.
Two common particle filters used to make water safe to drink are fiber and ceramic. Fiber filters are made out of cellulose, rayon, or another type of fiber. These filters have larger holes that will definitely trap dirt and particle-sized contaminants from getting through to your water, but they won't do much against liquid or dissolved contaminants like lead. Ceramic filters can do a tiny bit better, trapping asbestos fibers, bacteria, parasites, and other particles. They will not trap dissolved contaminants, either.
Carbon Water Filters
If you want the most complete type of water filtration, look into activated carbon filtration--it's the most effective at removing organic contaminants from water. Because organic contaminants or chemicals are most often what makes water taste, smell, or look "funky," carbon filters generally please most consumers. You may be wondering how these filters work, and what makes their methodology superior. When water passes through this type of filter, the carbon particles attract and remove contaminants (including dissolved substances fiber and ceramic filters can't get, such as hydrogen sulfide, lead, mercury, copper and chlorine).
Solid-block activated carbon filters are made up of a dense material that's packed with compressed and activated carbon particles. This filter has a larger surface area that's usually very successful in trapping contaminants. Another kind of drinking water filters are resin filters. They can trap contaminants like lead and other heavy metals, as well as minerals that cause deposits in kettles and coffee makers. The resin filters have an electrical charge (opposite of the charge held by contaminants), and that's how they attract contaminants right to them.
