What should be communicated after a changeover is complete?

The appropriate communication after a changeover is complete is to state, "Water supply established." This message is crucial as it confirms to all involved that the essential resource—water for firefighting operations—is now readily available at the scene. This assurance is critical for the safety of the personnel and the effective execution of their duties.

Communicating that the water supply is established ensures that all team members, including those waiting to engage in firefighting efforts, are aware that they can proceed with their operations without delay. It emphasizes readiness and allows for a seamless transition between teams, which is fundamental in emergency situations.

The other options, while important in various contexts, do not address the immediate operational concern of securing the water supply, which is vital during firefighting activities. Hence, recognizing and communicating the establishment of the water supply is essential for coordinating a safe and effective response.