A plumbing fixture (10,10 I,10 II,10 III) comprising: a water delivery part (12,12 I,12 II,12 III) comprising a first housing part (14,16;14 I,16 I;14 II,80;14 III,16 III) having a water outlet (24,24 I,88,24 III) and a hollow interior channel communicating with said water outlet (24,24 I,88,24 III) and defining an open inlet opposite to said water outlet (24,24 I,88,24 III), said first housing part (14,16;14 I,16 I;14 II,80;14 III,16 III) further having a first connector (28,30) at said open inlet, a filter cartridge comprising a second housing part having a hollow and generally elongated and cylindrical shape, said second housing part having a first end and an opposite second end and being positionable in an at least partial insertion in said hollow interior channel through said open inlet exposing said first end outside said first housing part (14,16;14 I,16 I;14 I,80;14 III,16 III) and positioning said second end in communication with said water outlet (24,24 I,88,24 III), said first end defining an inlet connector connectable to a source of water through a plumbing fitting (74,104,106,120) and establishing communication from said source of water into said second housing part, said second housing part further having a second connector (52,54), said filter cartridge further comprising a capillary filter interposed and concealed within said second housing part between said first end and said second end, and said second connector (52,54) being engageable and lockable with said first connector (28,30) for retaining said second housing part in said at least partial insertion, said first connector (28,30) being non-connectable to said plumbing fitting (74,104,106,120), and the second housing part is retained in the insertion within the hollow interior channel by the engaging and locking of the sealing rings (52, 54) of said second connector with the respective first and second grooves (28, 30) of said first connector. a water delivery part (12,12 I,12 II,12 III) comprising a first housing part (14,16;14 I,16 I;14 II,80;14 III,16 III) having a water outlet (24,24 I,88,24 III) and a hollow interior channel communicating with said water outlet (24,24 I,88,24 III) and defining an open inlet opposite to said water outlet (24,24 I,88,24 III), said first housing part (14,16;14 I,16 I;14 II,80;14 III,16 III) further having a first connector (28,30) at said open inlet, a filter cartridge comprising a second housing part having a hollow and generally elongated and cylindrical shape, said second housing part having a first end and an opposite second end and being positionable in an at least partial insertion in said hollow interior channel through said open inlet exposing said first end outside said first housing part (14,16;14 I,16 I;14 I,80;14 III,16 III) and positioning said second end in communication with said water outlet (24,24 I,88,24 III), said first end defining an inlet connector connectable to a source of water through a plumbing fitting (74,104,106,120) and establishing communication from said source of water into said second housing part, said second housing part further having a second connector (52,54), said filter cartridge further comprising a capillary filter interposed and concealed within said second housing part between said first end and said second end, and said second connector (52,54) being engageable and lockable with said first connector (28,30) for retaining said second housing part in said at least partial insertion, said first connector (28,30) being non-connectable to said plumbing fitting (74,104,106,120), and the second housing part is retained in the insertion within the hollow interior channel by the engaging and locking of the sealing rings (52, 54) of said second connector with the respective first and second grooves (28, 30) of said first connector.