REVERSE OSMOSIS SYSTEMS Although Reverse Osmosis seems like a complex system it is really a simple and straightforward water filtration process. And it's not a new process. High-pressure (pump driven) reverse osmosis systems have been used for years to desalinate* water – to convert brackish or seawater to drinking water. Having a better understanding of how a reverse osmosis system works will eliminate the mystery and confusion you may feel when you look at a reverse osmosis system - with its many colored tubes and multitude of filters. Reverse Osmosis is a process in which dissolved inorganic solids (such as salts) are removed from a solution (such as water). This is accomplished by household water pressure pushing the tap water through a semi permeable membrane. The membrane (which is about as thick as cellophane) allows only the water to pass through, not the impurities or contaminates. These impurities and contaminates are flushed down the drain.