The activated charcoal found in many water filters is an effective ingredient for removing harmful chemicals from the water. It is able to virtually eliminate the presence of chlorine and many chlorine hydrocarbons; heavy metals such as lead, mercury, aluminum, cadmium, chromium, and copper; and all pathogenic bacteria. These would include E. Coli, Klebsiella, Pseudomonas, Giardia, and others. It can also remove nitrates and nitrites often found in fertilizers.
Charcoal is simply the carbon residue of the destructive distillation of wood. Carbon is the sixth element on the Periodic chart, making up 18% of the mass of your body. Its remarkable ability to combine with other chemicals results in more chemicals in nature made with carbon than those without.
Activating carbon makes it more effective as an adsorbing agent. Charcoal is treated with oxygen to greatly increase its surface area. After this treatment, the surface area of activated charcoal is increased to an amazing three hundred to two thousand square meters per gram! This allows liquids and gases through and gives more places for the adsorption process to take place.
Adsorption means the impurities are chemically bounded to the surface of the charcoal. Thus, the more surfaces, the more impurities are removed. However, even with this tremendous surface area, the places to bond an impurity constantly decrease and eventually it is ineffective.
At this point the filter must either be replaced or recharged. Recharging involves back washing water through the filter and scrubbing every accessible surface. In other words, do what you can to remove the impurities so that the surface can adsorb once more. Of course, eventually it is impossible to clean a filter and it must be replaced. Under normal use, the estimated lifespan of an activated charcoal water filter is about a year.
What factors determine how effective a filter will be? First, since the greatest surface area is desirable, the pore size and distribution of the pores will determine how effectively a filter works. Second, the size of the impurities will vary. Large organic molecules are absorbed better than smaller ones. Third, the more acidic the water, the better adsorption works. Fourth, adsorption works better in cold water than in warm water. Fifth, how long will the contaminants be in the presence of the charcoal? The longer it is between the time water enters the filter and the time it leaves, the more filtering takes place.
Most of the impurities in water are invisible and odorless. Thus, you do not detect them until they have done their damage. What are the effects of ingesting heavy metals, for example? We are only beginning to discover the answer to this.
Even if you think your water source is safe, or if you use city water and trust that it has been tested, it is best to filter drinking and cooking water. At the very least, the filtering will remove the chlorine added to the water to keep it safe until it reaches the homes. Why take a chance when the health and safety of yourself and your family is at stake?
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