Reverse osmosis (RO) Systems combine the latest technologies in water filtration for residential use, membrane separation (reverse osmosis), activated carbon adsorption, and conventional filtration, to reduce a wide spectrum of contaminants that can be found in water. RO filters remove contaminants from drinking water by pushing them through a membrane with tiny pores that blocks particles larger than water molecules.

A reverse osmosis water filter can remove a wider range of pollutants than other types of filters. Also as per the EWG, an RO system is effective at removing many contaminants not removed by activated carbon alone, including arsenic, fluoride, hexavalent chromium, nitrates and perchlorate. An RO system combined with carbon filter is most effective at removing water contaminants including chlorine, trihalomethanes and VOCs.