Method and filling device for filling a transport container with a fluid

In a method for filling a transport container (12) with a fluid, the fluid is repeatedly conveyed through the cleaning device (7) in a cleaning circuit (1), and a contamination factor of a fluid sample amount in the cleaning circuit (1) is determined with a contamination measuring device (15), wherein a filling process of the transport container (12) with the fluid only ends once the contaminationfactor falls below a first threshold value. The fluid sample amount provided for determining the contamination factor can be channeled off from the cleaning circuit (1), supplied to the contaminationmeasuring device (15) and, after the determining of the contamination factor, supplied back into the cleaning circuit (1). In a container cleaning step, a container fluid amount previously introducedinto the transport container (12) from the cleaning circuit (1) can be removed from the transport container (12) again and supplied back into the cleaning circuit (1). A contamination factor of the container fluid amount remov