The activated carbon filter is used to remove the active chlorine, colour, foul smell and other organic materials in water  in order to protect the reverse osmosis membrane against biological contamination and oxidative damage. 

The activated carbon is made of wood, coal and nut shell with carbon by chemical or physical activation method. It has a lot of micropores and huge specific surface area, thus has very strong physical adsorption capacity, and can effectively adsorb the organic pollutants in water. In addition, in the process of activation,  the oxygen containing functional groups form on the  amorphous part of activated carbon surface, such as: Carboxyl, hydroxyl and so on, these groups make activated carbon have the performance of chemical adsorption, catalytic oxidation and reduction, they can effectively remove the residual chlorine and some metal ions in water .