Carbon filters have been considered the oldest means of water purification as they have been in use for hundreds of years, as far back as 2000 BC. Activated carbon has a slight electro-positive charge added to it, making it even more attractive to chemicals and impurities. One pound of carbon contains a surface area of roughly 125 acres and can absorb literally thousands of different chemicals. As the water passes over the positively charged carbon surface, the negative ions of the contaminants are drawn to the surface of the carbon granules.

Activated carbon filtration is very common in a number of home water treatment systems. It can be used as a standalone filter to reduce or eliminate bad tastes and odors, chlorine, and many organic contaminants in municipal (pre-treated or chlorinated) water supplies to produce a significantly improved drinking water. It is also very commonly used as a pre-treatment as part of a reverse osmosis system to reduce many organic contaminants, chlorine, and other items that could foul the reverse osmosis membrane.

ATEK Water Systems has various carbon filters for a wide range of applications.