Never add water to cooking oil near an open flame. This can cause a dangerous explosion as the water rapidly turns to steam and splatters the hot oil.
Adding water to hot cooking oil is extremely dangerous due to the vast difference in their boiling points and densities. Water has a boiling point of 100°C (212°F), while cooking oil is typically much hotter, often exceeding 175°C (350°F) during cooking. When water comes into contact with the hot oil, it instantly vaporizes into steam. This rapid expansion of water into steam causes the hot oil to splatter violently, potentially causing severe burns and spreading the fire. Furthermore, because water is denser than oil, it sinks to the bottom of the pan before vaporizing, exacerbating the explosive effect. The sudden expansion can even cause the pan to overflow or shatter.
If a grease fire occurs, never use water. Instead, smother the flames with a lid, baking soda, or a fire extinguisher rated for grease fires.