Patent ID: 8216463

Claim:
A water filter cartridge, comprising: an outer housing; a water filtration media inside the housing; and a cap affixed to an end of the housing to thereby enclose the filtration media, the cap having a rim with a pair of flanges for engaging a manifold of a water filtration system to hold the filter cartridge in an operative position when twisted in the manifold, the cap having a first portion defining a large female cylindrical cavity positioned between the flanges and sized to receive a large male cylindrical body of the manifold and a second portion defining a small cylindrical cavity concentric to the large female cylindrical cavity and depending in an axial direction, the small cylindrical cavity being sized to receive a small male cylindrical body of the manifold, the first portion of the cap that defines the large cylindrical cavity having an inlet port positioned to allow the inflow of unfiltered water from the manifold for passage through the filtration media, the second portion of the cap that defines the small cylindrical cavity having an outlet port positioned to allow the outflow of filtered water to the manifold, an annular sealing member seated in the large cylindrical cavity, and the first portion of the cap that defines the large cylindrical cavity having a channel formed therein which is positioned so that the annular sealing member provides a substantially water-tight seal when the filter cartridge is in the operative position and the annular sealing member prevents water from otherwise flowing through the channel and externally of the water filtration system; whereby when under normal water pressure the water filtration system will immediately visually exhibit a substantial leak if the filter cartridge is coupled to the manifold of the water filtration system in the operative position without the annular sealing member being positioned in the large cylindrical cavity.