Abstract

A water filter cartridge has a cylindrical shell. A conduit runs between closing end walls and is disposed within a filtration material. There are additional openings in the respective end walls for communicating the flow of water through the material. A water filtration element of a porous medium is shaped to nest within a portion of the shell encircling a corresponding portion of the filtration material and defining space between the medium and the inner side wall of the shell with that space being in the water flow path from one of the end walls and the material through the medium. A reference color is exhibited over a portion of the exterior side wall of the shell adjacent to the location of the medium inside the shell, and the medium exhibits a given color upon beginning of usage but changes color with continued usage in response to its entrapment of matter in the water. The shell is transparent over the medium to enable the user to compare the medium color to the reference color. The filtration material is secured in place by a plug forming one of the end walls and which has an opening around its periphery with a water pervious ring being sandwiched between that peripheral opening and the space defined on the outside of the filtration medium.