Reverse Osmosis (Domestic R. O. System) based water purification systems are the best available systems, which can remove almost all kinds of impurities / contaminants present in water. These include inorganic chemicals, organic compounds, heavy metals, pesticides, microbes etc. Purity of RO system treated water approaches that of distilled water. Purification by Reverse osmosis based systems does not depend on the quality of raw water and can purify water containing all types of impurities. The reduction of Total Dissolved Solids (TDS) in water by RO membrane is 90-97%.