A water transport assembly, is provided including a housing having a first chamber therein, which is accessible through an opening in the housing. The housing additionally includes a sample inlet port and a sample outlet port, both of which are in fluid communication with the first chamber. A flat ion exchange membrane is attached to the housing in a plane over the opening in the housing, to seal the opening in a vapor tight seal. Water will pass through the membrane based upon the vapor pressure on each side of the membrane, to either dry or humidify sample passing through the first chamber. When the flat ion exchange membrane is a flat, thin ion exchange membrane it is preferable that the thin ion exchange membrane have a thickness of between about 0.1 and about 3.0 mils.