The Undersink Reverse Osmosis is neatly installed under the sink with a dedicated faucet installed above the sink. This system has a storage tank which automatically refills the level of water as you use it with a method purely based on pressure (no electricity) in the mains to operate the system of check valves, automatic shut off valve and diaphragm. When faucet is turned on, water comes out of the storage tank then automatically replaces the used amount of water and automatically turns itself off once it is full. Reverse osmosis membrane is made from what is called Thin Film Composites (TFC) also called polyamide (PA) membranes. These membranes filter the water at around 0.0005 microns, which is about ½ a millionth of a millimetre, it is so fine that it can strain salt out of the water. The RO membranes work down to the molecule structure of water (H2O), if a molecule of water has an extra atom attached such as a carbon atom the molecule is too large to fit through ...