Reverse Osmosis produces one of the purest forms of water available. It consists of three pre filters, after which the water passes through a membrane which rejects all contaminants including bacteria. These systems produce a relatively small amount of ultra pure water, starting from 180 litres per day. The water is therefore stored in a pressurised tank. It then flows from the tank through a final polishing filter before feeding a tap which will need to be installed in your counter. Reverse Osmosis requires a minimum pressure of 2 bar for this system to function efficiently.