The supply device for dialysis apparatuses, comprising a permeate line and at least one concentrate line for supplying permeate and dialysis concentrate(s) to a dialysis apparatus to be mixed so as to obtain dialysis liquid, and comprising a waste water line for discharging waste water out of the dialysis apparatus, is characterized in that the waste water line is in communication with a substantially funnel-shaped outlet container into which the waste water falls in a free fall, thereby impinging on an inclined wall section of the outlet container. Virtually no noise is created that would be noticed by a patient, and a pivotable door is preferably arranged at the outlet container for permitting the taking of samples in an easy way from the outlet container by means of small test rods.