Undercounter filter system that uses carbon and KDF-55
Carbon has had a wide variety of uses over the years. One of these is filtering water. Carbon is used for it’s ability to absorbed. It can easily absorb odors, liquids and gases. The porous (the small void spaces in the carbon) properties of carbon gives it a large surface area.  Even very small pieces have a larger surface area than one would think.

You hear the terms activated carbon, activated charcoal or activated coal. These are all a form of carbon derived from charcoal. The carbon used can be produced from nutshells, coal or wood. 

Activated carbon usually caries a positive charge. Any water contaminants with a negative charge are attracted and stay with the filter. This makes it effective at reducing chlorine, volatile organic compounds (VOC’s) and sediment. Minerals, salts or dissolved inorganic compounds are not affected.

Catalytic activated carbon is used for it’s ability to remove chloramines from city tap water. Catalytic part brakes down the chloramines so the activated carbon can absorb what it is made of.

Carbon filters are usually of two types. Formed carbon blocks and granular. Home water filters use a variety of sizes of formed carbon blocks. This increase the surface area the water will come in contact with. By increasing the surface area this helps improve it’s ability to reduce a larger amount of contaminants. This also improves the particle size that is removed. Particle size can range from 0.5 to 50 microns.

Today you see some water filters that combine carbon filtration with the addition of KDF-55 or silver. The KDF-55 or silver prevents the growth of bacteria from growing in the filter. Normal carbon filters have a lot of surface area that are ideal areas for bacteria to grow, but does not kill it. As the filter ages bacteria keeps growing until it start traveling out in to the produced water. This can produce water with a higher bacteria level than regular tap water has.