R/O is a technical breakthrough initially developed by the U.S. government to provide fresh drinking water for the Navy. The Reverse Osmosis process uses waterline pressure to push raw tap water against a special semipermeable membrane. In this sophisticated molecular squeezing process, H20 molecules tend to separate from the contaminants in your tap water. The water molecules then pass thru to the inside of the membrane, and on to the reservoir - ready for our fresh daily use. The rejected particles and contaminants are washed from the membrane and down the drain.