Reverse osmosis reversely uses a semiperme able membrane of the osmosis phenomena in nature. It is effective for 99% removing minerals/ionized inorganic matters/numero us impurities/ bacteria/germs which are contained in water a lot, SS which polluted underground water contains, rust stain and iron in waterworks, and secondary compounds in some waterworks flown from industrial waste water (300 molecular weight or more).   

It is used for the pretreatment of ultra-pure water for semiconductors, and it is extensively applied to various water purification treatments (i.e., changing sea water into fresh water).