What procedure should follow if there's an issue with the lavatory system during flight?

The appropriate response when there is an issue with the lavatory system during flight is to inform passengers to use other facilities. This step is crucial for maintaining passenger comfort and hygiene while ensuring that the flight can continue without unnecessary delays. By directing passengers to alternate restroom options on the aircraft, as well as ensuring they understand the temporary situation, cabin crew play a key role in managing the inflight experience effectively.

Communicating directly with passengers helps to alleviate any concerns they might have about the lavatory issue and allows them to plan their uses of the facilities accordingly. This approach also minimizes disruption to the flight schedule, allowing the crew to focus on other necessary procedures, such as managing the flight or notifying ground control if needed. In this context, the other options involve actions that may be part of a checklist for addressing technical issues, but the immediate priority is passenger comfort and communication.