The disclosure relates to a paint supply system for a coating installation (e.g. painting installation) comprising a ring line for circulation of a coating agent, a ring line tapping point in the ring line for extraction of the coating agent from the ring line, a consumer and a tap line leading from the ring line tapping point to the consumer. The disclosure provides a device for alternately moving the coating agent forward and backward in the tap line to avoid settling of the coating agent in the tap line.