The reliable RO membrane is an important component of each RO system. Each membrane element requires a special RO membrane housing. The purpose of the RO membrane housing is to create the proper conditions for the RO membrane to operate efficiently producing clean water under the applied pressure. The RO membrane housing distributes the flow of feed water into concentrate and permeate water. It isolates the “permeate” (clean) water from the feed water and the concentrate. There are two main types of reverse osmosis membrane elements: spiral wound and hollow fiber membrane elements. The spiral wound elements are mostly used to produce drinking water while hollow fiber is used in the treatment of waste water and other special cases. The spiral wound RO membrane elements are made from packets of RO membrane flat sheets, permeate and concentrate spacers. Those packets are rolled around a core tube to form cylindrical shaped membrane element that can fit into a tubular RO membrane housing.