A device for monitoring the functioning of a rotating liquid-discharging appliance includes at least one collecting chamber with at least one inlet orifice, at least one outlet orifice, and at least one sensor. The outlet orifice of the collecting chamber has a smaller cross section than the inlet orifice, and the sensor is a level sensor that transmits signals to an evaluation apparatus, by which an entire functioning of the rotating liquid-discharging appliance can be monitored. The monitoring device is disposed approximately in a region acted upon with liquid by the appliance to be monitored.