ro-Reverse Osmosis pretreatment process is mainly activated carbon and fine filtration. Infiltration is a natural phenomenon: water passes through a semi permeable membrane, from the low solute concentration side to the high solute concentration side until the solvent chemical level reaches a balance. Balance, the pressure difference between the two sides of the membrane equals osmotic pressure. This is the phenomenon of osmotic effect (osmosis). Reverse osmosis is that if the high concentration of the side of the pressure, it can be mentioned above the osmosis effect to stop and reverse, so that the water from high concentration to the low concentration of the side, to purify. This phenomenon is known as reverse osmosis (reverse osmosis), a semi permeable membrane called the reverse osmosis membrane.