How does water extinguish fires?

Water extinguishes fires primarily through the cooling effect it provides. When water is applied to a fire, it absorbs heat energy from the burning materials, lowering their temperature. This cooling process is crucial because most combustible materials need to reach a specific temperature to sustain combustion. By reducing the temperature below this threshold, the fire cannot maintain itself and eventually goes out.

In addition to its cooling properties, water also works by turning into steam when heated. This phase change not only helps in absorbing additional heat but also creates a barrier that can displace oxygen from the combustion zone. However, the primary mechanism at work is the cooling of the flames and the fuel, which is vital in fire suppression.

Other methods of extinguishing fires, such as smothering and displacement, involve depriving the fire of oxygen or separating it from combustible materials, but water's ability to cool is the most effective and widely used method in firefighting.