a first connector of a connector assembly of a sterile batch container can be unsealed . the connector assembly can be attached to a filling port of the sterile batch container and can have a sterile filter arranged between the filling port and the first connector . the first connector can be coupled so as to receive produced purified water . a transmembrane pressure can be monitored across the sterile filter while flowing the purified water through the connector assembly into the sterile batch container so as to provide a sterile fluid stored therein . the connector assembly can be detached from the filling port of the sterile batch container . after the detaching , the sterile batch container can be coupled to the blood treatment system . in response to a change in the transmembrane pressure exceeding a predefined level , an alarm signal can be generated .