Abstract: A method and apparatus for removing arsenic from water at point of entry or point of use particularly for residential application. The point of entry system comprises a first stage having a manganese greensand oxidizer to convert arsenite (As+3) present in the water to arsenate (As+5) and a second stage for passing the water through an anion exchange resin. Each stage includes a control head for automatic regeneration at a predetermined frequency. The manganese greensand is regenerated with a solution of potassium permanganate and the anion exchange resin is regenerated with a salt solution. An alternate embodiment for point of use application comprises a manganese greensand oxidizer cartridge to convert arsenite (As+3) to arsenate (As+5) followed by removal of the arsenate (As+5) with a reverse osmosis system.