4 x 3rd stage: 5 micron CTO Carbon block absorbs any residual chlorine, tastes and odors, Plus compounding pre-filters' Efficiency and extending RO membrane's life 4 x 2nd stage: 5-micron granular activated carbon absorbs unpleasant chlorine, tastes and odors, cloudiness and colors 4 x 1st stage: 5-micron 10"x2.5" universal sediment filter cartridge,15000- Gallon 1 x reverse osmosis membrane (50 GPD), capable of processing 50 gal. Of water per day 2 x 5th stage: 1-micron total polishing inline Carbon absorbs any possible residual tastes and odors