Abstract: An element for a reverse osmosis water purification cartridge consists of a long rigid plastic tube having peripheral V-shaped grooves along its length. A nylon monofilament is helically wrapped along the length of the element with wrap spacings of about 1/3-2/3 of the fiber diameter. The element is formed by placing liquid membrane-forming material on the wrapped tube; the membrane intrudes 1-2 mils between the adjacent wraps of monofilament.

Abstract: A reverse osmosis element consists of a long tubular plastic base having a plurality of elongate parallel channels in its exterior surface. A monofilament strand is wrapped or extruded helically around the surface of the base, and a semipermeable membrane is formed, e.g. by casting or extrusion, around the wrapped tube. The tubes are mounted in a hollow cylindrical housing on a manifold; a passageway for purified water extends through the membrane, along the channels to the interior of each element, from the interior of each element through the manifold to a collection chamber, and to a purified water outlet.