Why should water not be used on gasoline, oil, or grease fires?

Using water on gasoline, oil, or grease fires is problematic because water has a lower density than these flammable liquids. When water is applied to such fires, it does not adequately cool or extinguish them. Instead, the water can cause the burning fuel to spread, as the water forces the burning liquid to splatter or disperse. This can lead to a larger area being engulfed in flames, making the situation significantly more dangerous.

The behavior of these materials creates a situation where adding water exacerbates the problem rather than solving it. Effective fire-fighting tactics for these types of fires typically involve using specific extinguishing agents, such as foam, dry chemical, or CO2 extinguishers, designed to handle burning liquids. Understanding the nature of the materials involved is crucial in effectively and safely combating fires.