The invention relates to an aseptic pump housing with switchable drainage, especially for an impeller housing or spiral housing or for a housing of a centrifugal pump for delivering liquids under aseptic or at least sanitarily proper conditions, said housing forming a vaneless annulus. The inventive pump housing is designed such that it does not have sump and clearance volume in the area of the drainage discharge and such that it can be emptied without leaving any residual matter. To this end, the end of the drainage opening (1b) which is situated on the side of the pump housing merges into a seating (1c), and a closing element (2a) is provided which interacts with the seating (1c) thus closing the drainage opening (1b) and, when in the closed position thereof, closes with the inner wall of the pump housing (1) in a manner which is flush and free of clearance volume.