A method and system for cleaning of milking systems—creates slugs of cleaning liquid in milking systems in response to the detection of the presence of cleaning liquid. The milking system includes a milk conduit (3), a liquid sensor (4) for detecting the presence of liquid in the milk conduit (3), a vacuum source (7) for applying a suction pressure to the milk conduit and cleaning equipment (12, 13) including elements supplying cleaning liquid into the milk conduit and an air injector (16) arranged to supply air into the milk conduit, the system being adapted to supply cleaning liquid into the milk conduit, apply a suction pressure to the cleaning liquid and supply air so that a liquid slug is created that flushes the milk conduit. The liquid sensor (4) is adapted to sense the presence of cleaning liquid supplied to the milk conduit, and the system is adapted to supply the air based on the detection of the presence of cleaning liquid. The sensing of the sensor (4) is also used for evaluating performance of cleaning operations.
