How is a fire suppressed with water?

Using water to suppress a fire is effective primarily due to its ability to cool the flames. When water is applied to a fire, it absorbs heat from the flames and surrounding materials. This cooling effect reduces the temperature of the combustibles below their ignition point, eventually leading to the extinguishment of the fire.

Furthermore, as water turns into steam upon contact with the intense heat, it expands significantly, which can help displace oxygen in the immediate area and further suppress the flames. This dual-action of cooling and displacing oxygen is why water is a common suppression method for many types of fires.

The other answers present concepts that do not correctly represent the role of water in fire suppression. For example, the idea that water creates more steam and intensifies the fire misrepresents how water interacts with heat. Similarly, stating that water merely covers the fire to prevent oxygen access overlooks the essential cooling role water plays. Lastly, suggesting that water must be mixed with chemicals before application is misleading, as plain water is often effective on its own in many fire situations.