1. Characteristics of RO Membrane 1) R/O Membrane Filter eliminates all pollutants such as heavy metals, virus, bacteria and organic chemicals through stomata with the size of 0.0001 μm , which is 1/1,000,000 of the thickness of human hair 2) R/O Membrane separates organic chemicals better than inorganic chemicals and electrolytes better than non-electrolytes. R/O Membrane can eliminate not only the substances of particle nature but also the substances of ionic nature, the particle size of which is very small. 3) R/O Membrane separates substances without changing the phase of the substances and is applicable to various fields as it has good physical and chemical durability. 2. Superior Rejection Rate of R/O Membrane (Rejection, %) Substances Rejection Rate (%) Ions 99+ Nitrates 95 Organics 95 THM 99+ Silica 98+ Bacteria and Particles 100% Dissolved gases Unable to eliminate 3. Reverse Osmosis Phenomena   When solutions which have differences in concentration is separated by semi-permeable membrane, the water solution with low concentration moves toward high concentration side after lapse of certain time making difference in water level which is called osmosis phenomena. The difference in water level generated at that time is called osmotic pressure while water solution with high concentration moves toward low concentration side if a pressure that is higher than osmotic pressure is given to the solution with high concentration, which is called Reverse Osmosis phenomena.