Abstract: A water filter cartridge includes a reverse osmosis membrane permeator spirally wound on a central winding tube and surrounded by an impermeable barrier layer which is, in turn, surrounded by a spirally wound prefilter. A post-filter is placed centrally within the winding tube. The cartridge is designed for functional installation in a housing tube fastened and sealed to a valve plate at a first end and closed by a removable end cap at the other, second end. Feed water enters the cartridge through an inlet port in the valve plate at the first end at an outer radius to pass lengthwise in prefilter. Prefiltered water returns from the second end lengthwise through the reverse osmosis permeator to a waste-water outlet port in the valve plate at an intermediate radius. Product water which has permeated through the membrane flows inwardly through holes in the winding tube and into a clearance space surrounding the central post-filter.

Abstract: "A water purification system has a reverse osmosis filtration unit which receives feed water from a feed water valve and separates it into product water and waste water. A reservoir has a movable separator dividing it into a product water chamber for receiving the product water and a control water chamber. The product water is delivered to an outlet connection from the product water chamber or directly from the filtration unit. A regulator is connected to the waste water outlet port of the filtration unit, the control water port of the reservoir, and a drain line. The regulator has a first valve for providing waste water from the filtration unit to the control water port of the reservoir for urging the separator toward the product water chamber. The regulator has a second valve that can rapidly drain water from the control water chamber of the reservoir and rapidly reduce pressure in the control water chamber, thus facilitating the refilling of the product water chamber.