An ion exchange filter apparatus , in particular for a fuel cell system, having a housing accommodating an ion exchange cartridge , wherein the housing comprises a cover , wherein the housing features at least one inlet port and at least one outlet port for a medium, wherein the at least one inlet port and the at least one outlet port break through a wall of the housing , wherein a flow path extends from the inlet port through the ion exchange cartridge to the outlet port , wherein the ion exchange cartridge features a cartridge container having a receiving space filled with ion exchange material and delimited by a circumferential wall , which features one or a plurality of exit windows distributed at or across its circumference, wherein the exit window or windows of the ion exchange cartridge are offset in the axial direction (L) with respect to the outlet port of the housing , wherein the flow path downstream of the exit windows of the ion exchange cartridge features at least one deviation , in particular of at least 45 degrees, wherein the exit windows of the ion exchange cartridge are disposed axially above the outlet port of the housing with respect to a gravitational direction in a mounting position, characterized in that the outlet port is disposed in an upper third of a housing height of the housing and in that the wall of the cartridge container is connected to the cover of the housing in a material locking manner, wherein the cover features an overlapping area , which completely overlaps the exit windows in the axial direction (L) by forming an annular gap and wherein a flow path of a medium through the ion exchange cartridge downstream of the exit windows features the deviation within the annular gap . wherein the housing features at least one inlet port and at least one outlet port for a medium, wherein the at least one inlet port and the at least one outlet port break through a wall of the housing , wherein a flow path extends from the inlet port through the ion exchange cartridge to the outlet port , wherein the ion exchange cartridge features a cartridge container having a receiving space filled with ion exchange material and delimited by a circumferential wall , which features one or a plurality of exit windows distributed at or across its circumference, wherein the exit window or windows of the ion exchange cartridge are offset in the axial direction (L) with respect to the outlet port of the housing , wherein the flow path downstream of the exit windows of the ion exchange cartridge features at least one deviation , in particular of at least 45 degrees, wherein the exit windows of the ion exchange cartridge are disposed axially above the outlet port of the housing with respect to a gravitational direction in a mounting position, characterized in that the outlet port is disposed in an upper third of a housing height of the housing and in that the wall of the cartridge container is connected to the cover of the housing in a material locking manner, wherein the cover features an overlapping area , which completely overlaps the exit windows in the axial direction (L) by forming an annular gap and wherein a flow path of a medium through the ion exchange cartridge downstream of the exit windows features the deviation within the annular gap . <EOS>