In an apparatus for treating containers with a medium, the containers are transported cyclically in groups. A linear holding device has a plurality of container holders for holding the containers in a suspended state. A treatment device has a plurality of outlet heads that are connected to a supply line for the medium via respective branch lines. The outlet heads are moved together as a group in the vertical direction. Each outlet head has an outlet line for discharging the medium into the containers. For the purpose of treating the container, the outlet line is introduced into the container, which is held in a suspended state in the container mount. Each outlet head is assigned a controllable restraining mechanism. A controller communicates with the restraining mechanism to control a restraining element to hold back the outlet line of a respective outlet head in a restraining position as required.