A combination of a single-station reverse-osmosis (RO) device comprising a hemodialysis device (HD device) is characterized in that a connection line is provided with a buffer chamber for permeate which serves on the one hand a faster permeate supply into the HD device and on the other hand a generation of a negative transmembrane pressure, and that upon request by the HD device the permeate flows either via the water inlet valve into the HD device or via a flushing valve of the HD device to an outlet.
