Method for controlling one or more vacuum generators (1) and thereby the vacuum in a vacuum sewage system, in particular controlling one or more liquid ring screw pumps in such system, including beyond the generator/s (1) one or more tubular collectors or suction pipelines (2) connected to the vacuum generator and one or more toilets, urinals, grey water sinks etc (3, 4), connected to the suction pipeline through branch pipelines (6). The rotational speed of the vacuum generator (1) is controlled on the basis of the set vacuum requirement.