What should be the first action if a portable water tank is unable to supply water?

When a portable water tank is unable to supply water, the first action to take is to report to command and find alternative sources. This is crucial because the chain of command ensures that operations are coordinated and that everyone involved is aware of the situation. By reporting to command, the team can mobilize additional resources or adjust strategies based on the availability of water from other potential sources or tanks.

Finding alternative water sources is vital to maintaining firefighting efforts and ensuring the safety of both the personnel involved and any civilians in the area. In emergency situations, having a clear understanding and communication with command allows for a quicker and more effective response to address the issue at hand.

The other options, while potentially relevant later in the process, do not address the immediate need for coordination and resource identification required in this scenario.