If you’ve been learning a little about water filters because you’re convinced of the benefits of drinking clean purified water you will have come across “charcoal water filters” or “carbon water filters” or “activated carbon water filters”. What are these?
Charcoal water filters are filters that use charcoal to remove the contaminants in water during the filtration process. Charcoal is carbon that is created by heating organic matter in the absense of oxygen to high temperature. Commonly coconut husks are used for the organic material.
There are various properties to carbon, and the one that is important for the purposed of water purification is that it is extremely porous, having huge numbers of tiny holes. This allows the water and it’s contaminants to pass through the holes and come into contact with the carbon. The contaminants are chemically attracted to the carbon and so are “absorbed” by it, and don’t pass through.
That is what charcoal, or carbon, water filters are. So what are activated carbon, or what is known as AC, filters? These filters use a form of carbon that is way more porous than normal carbon, and this is created during the manufacturing process.
In fact it is so porous that it can have anywhere up to 20000 or more square yards of surface area for each ounce of carbon. Now that’s really porous.
Because the carbon filter absorbs contaminants it slowly fills up with these contaminants, so needs to be replaced periodically.
An activated carbon water filter works well filtering a wide range of contaminants, but doesn’t filter all of them, and for this reason the best water filters use a multi stage water filtration process. Not only is the carbon block, or activated carbon filter used but there is a second stage to the process that removes the contaminants that are not removed by activated carbon filtration.
But there is no reliance on carbon filtering alone in the best water filters, because it is recognized that it is inadequate to rely on AC on it’s own due to it’s inability to remove some contaminants. So there is a second stage that filters out these contaminants by other processes, like using ion exchange to exchange lead ions for harmless potassium ions to remove lead from the water.
And there are two extremely dangerous potential water contaminants, cryptosporidium and giardia, and these must also be removed by the best filters. This is done by use of an extremely fine filtration process.
So that’s the basics of water filtration by charcoal, or carbon. The best water filters use activated carbon as a filter medium, but due to it’s limitations supplement the actions of the carbon filtration with other filtration methods to target the contaminants not removed by the carbon filtration. Like lead. You should expect around 99% of lead to be removed by the best water filters.
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