The device has permeate and concentrate lines for supplying permeate and dialysis concentrates to a dialysis device, respectively. The permeate and dialysis concentrates are be mixed to obtain a dialysis liquid. A waste water line discharges waste water out of the dialysis device. The waste water line stays in connection with a funnel-shaped outlet container (1), where the waste water falls into the outlet container in a free fall, so as to impinge on an inclined wall section of the outlet container. The outlet container is composed of a funnel (2), an upper lid (3) and a pivotable door (4).
