The Watts Premier Reverse Osmosis (RO) incorporates three different types of filtration technology in order to provide the best quality water to the user. The first stage is a sediment filter which removes larger particles and sediment from your water. The second and third stage with in our RO is our carbon block filter. Watts Premier uses only high quality independently certified carbon blocks. This additional certification on our carbon blocks ensures the consistency and integrity of the carbon block in each system we sell. These carbon blocks are able to reduce many contaminants with in your drinking water. The work horse of our system, the RO membrane, is next and is where the main filtration takes place to reduce any remaining contaminates or up to 97.9% of impurities in the water. The RO membrane is responsible for reducing many of the difficult water contaminants such as arsenic, chromium, radium and total dissolved solids. The fifth and final stage is a granular activated carbon filter which polishes your drinking water just prior to you drinking it. The combination of these technologies, mainly with the use of the RO membrane, is how the RO system can provide to you water that is bottled water quality.