Auto tds controller ro system manufactur in Rajkot Reverse Osmosis (RO) is a water purification process that removes contaminants from water by using a semi-permeable membrane. The basic principle behind RO is that water is forced through the membrane under pressure, leaving behind impurities like salts, bacteria, viruses, and other contaminants. The clean water that passes through the membrane is collected for use, while the waste water (which contains the contaminants) is discarded.