What is a critical action to take when draining a building?

Working down from the top floor when draining a building is critical because it helps to prevent the creation of additional pressure and potential flooding on lower levels. When water is removed from the highest points first, it allows for proper management of the water flow and minimizes the risk of structural damage that can result from a large volume of water accumulating in the lower levels. Additionally, this method ensures that any areas with potential trapped debris or blockages can be more effectively managed as the flow of water is directed down towards the drainage points, ultimately enhancing the efficiency of the entire draining process.

The approach emphasizes the principle of gravity, allowing water to flow downward naturally, thereby reducing the risk of backflow and making it easier to manage and redirect the water as it's being removed from the premises.