Patent ID: 7387729

Claim:
A replaceable filter cartridge for a standalone point of use water purification device, comprising: a housing having water inlet and water outlet ports that is adapted for removable insertion into said standalone point of use water purification device, wherein said water inlet and outlet ports are vertically spaced, with said water inlet port located to the top and said water outlet port located to the bottom of said housing; said housing having interior walls providing a flow path extending between said water inlet and water outlet ports along which water to be treated moves through concentric first inner and second outer fluid flow passageways containing flowthrough filter media, and a third flow passageway, wherein said third flow passageway is connected in fluid communication between said second flow passageway and said water outlet port, wherein said first and second concentric flow passageways are adapted to operate in tandem such that said water to be treated first moves through said first inner passageway containing flow-through filter media in a first, generally downward direction, and then moves through said second outer passageway containing flow-through filter media in a second, generally upward direction, and wherein said third passageway in fluid communication with said second flow passageway receives the water as it flows out of the second passageway and moves it along said third passageway in a generally downward direction to said outlet port located to the bottom of said housing; wherein the water that moves along the second, generally upward direction soaks upwardly through the filter media contained in the second passageway, which reduces if not eliminates channeling, and the opposing first and second flow directions provide self-wetting of the filter media contained in the first and second flow passageways, eliminating the need for post-use wetting, and wherein an outlet filter is provided within said third passageway that is adapted to prevent leakage of said flow-through filter media in said concentric first inner and second outer flow passageways at said outlet port located to the bottom of said housing and to control rate of flow of treated water through said third passageway on its way out said outlet port located to the bottom of said housing, and therewith to control the dwell time of treated water moving through said concentric first inner and second outer passageways of said flow path extending between said water inlet and water outlet ports.