Activated carbon is carbon which has a slight electro-positive charge added to it, making it even more attractive to chemicals and impurities. 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 filters used for home water treatment typically contain either granular activated carbon (GAC) or powdered block carbon. The two most important factors affecting the efficiency of activated carbon filtration are the amount of carbon in the unit and the amount of time the contaminant spends in contact with it. The more carbon the better. Similarly, the lower the flow rate of the water, the more time that the contaminants will be in contact with the carbon, and the more absorption that will take place.

All Trionics activated carbon filters use coconut shell carbon. There are two principal mechanisms by which activated carbon removes contaminants from water; adsorption, and catalytic reduction, a process involving the attraction of negatively charged contaminant ions to the positively charged activated carbon. Organic compounds are removed by adsorption and residual disinfectants such as chlorine and chloramines are removed by catalytic reduction.