Standard filter carbon reduces contaminants in two ways. It “adsorbs” chemicals by trapping and holding them, and to a smaller degree, it “chemisorbs” contaminants by changing them to something harmless. Chlorine, for example, can be “catalysed” to chloride. Catalytic carbon retains conventional carbon’s ability to adsorb contaminants but it also possesses a greatly enhanced capacity to catalyse, to promote beneficial chemical reactions.