Undersink reverse osmosis: 1.Standard 5 stage RO system 2.Food ... 5 micron sediment filter,it's effective removing dirt, rust and sand particles .Stage 2:(GAC)Granular activated carbon cartridge ,it ... Activated carbon block cartridge,remove chlorine and organic chemicals and reduce of tats,odor ,and color.Stage 4:(RO)Reverse osmosis membrane ... cooper,barium,mercury, sodium.Stage 5:T-33 post carbon filter