Reverse Osmosis directs water through a pre-filter to remove sediment, chlorine taste, odor, and particulate matter. Then, the water is forced through a semi-permeable membrane where a high percentage of the dissolved solids are rejected and flushed to the drain. Next, the storage tank holds the filtered water until you need it. Finally, an activated carbon filter removes tastes and odors. The final filter polishes the water immediately before going to the faucet for the purest taste.