Basically there are three styles of water filters, or more accurately, three varieties of water filtration methods. They are mechanical, chemical oxidation reduction (redox) and absorption. Following is an explanation of the way each works.
Mechanical Filters
This is simply having a barrier that has holes smaller than the material that you want to remove. This method of filtration removes minute substances that are floating in the water like dirt, silt, sand, sediment, rust and other un-dissolved elements. As water flows through the media the particles are held or inhibited and for practical purposes removed from your water.
Contingent on the class and/or type of the filtering media, particulates as tiny as 0.5 microns can be taken from the drinking water. For reference purposes, a micron is equal to 1/25,000 of an inch, the diameter of one filament of your hair is around 100 microns.
An assortment of materials are employed to manufacture mechanical filtration media. Ceramics and an assortment of resins cover the bulk of this mode of water filtering.
Oxidation-Reduction Process or Redox
Oxidation/Reduction Technology is a procedure in which electrons of one molecule are transferred to a different one. What this means is that if you blend two dissimilar metals you cause an electrochemical process that oxidizes a multitude of chemicals frequently discovered in ground water in addition to our civic water stores, thus taking them out of your water. The heavy metals such as lead, chromium, aluminum and cadmium are removed by the electrochemical process. Metals such as these are attracted to the filtration media, much like to a magnet.
KDF Fluid Treatment, Inc., produces the most extensively used media of this type, a coper and zinc alloy, and has held the patent ever since 1987.
Adsorption: Activated Carbon
Activated carbon absorbs organic substances which can cause your water to smell and taste bad. In addition it has the ability to get rid of chlorine, chlorimines and pesticides. This material is very porous having a vast surface area, to the extent that the carbon in a common countertop water filter could have a surface area of about 200 football fields.
The term “activated” refers to a method where the carbon becomes more porous than it is normally. Activation is achieved by using steam, a chemical process or by specific production processes while creating the carbon.
Activated carbon works like this: When water flows through the filter dissolved chemicals attach themselves to the carbon allowing the water to continue. This process is known as absorption.
Activated carbon can be grouped into three categories: granulated activated carbon (GAC), carbon block (CB) and powdered activated carbon (PAC). The carbon block variety is the choice for a faster flow, while the granulated activated carbon costs less and works acceptably with municipal water supplies. The PAC type is not use residentially as often.
The raw materials used for creating activated carbon are coal, wood, lignite, coconut shell and like materials. Coconut shell is thought of as the preferred material when creating filters for drinking water in light of its propensity to leave the water tasting better.
Be advised that water filters do not totally get rid of contaminates, filters will only reduce them. However a first-class water filter is going to remove most of the unwanted contaminants it is made to remove. Make it a point to buy only water filters certified by the National Sanitation Foundation (NSF) These filters are going to have been tested against their claims. In other words you are going to know what you are purchasing.
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