In a direct attack, water should be applied until:

In a direct attack, water should be applied until all visible flame is extinguished. This approach is crucial for effectively combating a fire, as visible flames indicate active combustion that poses a threat to life and property. When firefighters apply water to extinguish flames, they disrupt the combustion process by cooling the burning materials and displacing the heat, which ultimately leads to fire suppression.

While other indicators, such as a drop in smoke level or the fire darkening down, may suggest fire conditions are improving, they do not ensure complete extinguishment. The presence of smoke can persist even after flames are out, and if any fire remains, it can rekindle or reignite the situation, posing ongoing risks. Thus, ensuring all visible flames are extinguished is the most reliable criterion for confirming that the fire has been effectively controlled and the hazard mitigated.