Patent ID: 7909998

Claim:
A water treatment system comprising: a cartridge having: an external cartridge housing, the housing having a cylindrical portion with a top portion and a bottom portion, the bottom portion having a closed end, the top portion having a shoulder with a generally cylindrical neck portion extending upward from the shoulder, the cylindrical neck portion defining a portion of a connection fitting, the cylindrical neck portion defining a cylindrical bore having a cylindrical bore wall which defines a first diameter, the cylindrical bore wall having an annular ring protruding from the wall and defining a second diameter which is smaller than the first diameter; an internal cartridge housing within the external cartridge housing and having a top portion, with a shoulder, a tube portion extending upward from the internal shoulder, the tube portion defining an outlet bore, the tube portion defining an outer diameter having a third diameter, the third diameter is smaller than the first and second diameters, the tube portion and the annular ring define a cartridge inlet having an annular gap.