In this process, anion ions and cation ions which are in the water eliminate that are used to produce steam from the generator of steam sterilizers. Reverse Osmosis units are a top -level element of water purification which used in the most recent high-tech opportunities at the same time it is applied as an advanced filteration method. The principle of operating of these units can be explained with reverse operation of osmotic balance in nature. Reverse- osmosis system requires more pressure than osmotic pressure to reverse the osmotic balance. For this purpose, high pressure pumps are used in Reverse-osmosis systems. Water which pressurized by high-pressure pump is transmitted the membranes that have 5 angstorm sized pores. Water that is outgoing from the waste line is given into drainage. In this way, failures of sterile equipments which used for the operating room and the compo- nents of autoclave production reduce and their usage time will be longer. In short , reverse osmosis are an indispensable “water treatment” system of steam sterilizers.