Filling a container with a filling material having a first and second liquid components in a predetermined ratio includes supplying the first component from a tank to the container through a filling material line that defines opposite first and second directions, the line being closable by a valve. A flow-rate measuring unit determines an amount of first liquid component fed through the line in the second direction. The method also includes feeding the second component into the line, the line having been at least partially filled by the first component, and detecting an amount of the second component fed therein. Detecting the amount of the second component includes using a flow-rate measuring unit to detect motion of the first component caused by feeding the second component. The method then includes displacing at least a portion of the first component from the line along the first direction.