Reverse osmosis (RO): Is a water purification process that uses a partially permeable membrane to separate ions, unwanted molecules and larger particles from drinking water.... The result is that the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side.
Working of RO (Reverse Osmosis): Reverse Osmosis works by using a high pressure pump to increase the pressure on the salt side of the RO and force the water across the semi-permeable RO membrane, leaving almost all (around 95% to 99%) of dissolved salts behind in the reject stream. The amount of required pressure depends on the salt concentration of the feed water. The more concentrated the feed water, the more pressure is required to overcome the osmotic pressure.