WTF Fun Fact 12894 – Firefighters Use Wetter Water

It’s supposed to be one of those “duh” facts that water is wet. But did you know if can technically be “wetter”? Firefighters use “wetter” water to put out fires. This involves using synthetic chemicals to improve water’s ability to put out fires.

Why do firefighters need water wetter?

Some types of fires are so hot that water simply evaporated the moment it hits the flames. Wetting chemicals help increase water’s spreading and penetrating properties.

We’ve long known that fires involving oil and gasoline can’t be put out with a splash of water. Decades ago, fire departments started using chemical and mechanical foam and carbon dioxide to help extinguish those fires.

But even a fire that starts with a match may be hard to extinguish with plain old H2O. The material that’s burning may be too thick and dense for water to penetrate it and extinguish all of the flames, for example.

As a result, fire departments use water-wetting chemicals. These give water properties that allows it to maintain contact with a solid surface or spread out more effectively to address a wider area.

How can you make water wetter?

In firefighting, the purpose of water is to make other things wet. But when water bonds are cohesive, water can bead up and not penetrate the surface of an object. But adding detergents, water becomes wetter, the cohesive forces weaken, and it’s able to make other things wet – which in turn extinguishes a fire.

Wetting agents also reduce the surface tension of water by penetrating the water molecules and making them less adhesive. They can also help increase the evaporation temperature of water. For firefighters, this allows them to get things wetter faster and with less water.

The most common chemicals in wet water are surfactants such as ethylene or propylene glycol. They make water easier to distribute over a surface and better able to flow into things that are on fire.  WTF fun facts

Source: “Fighting Fires with “Wet” Water” — Fire Engineering


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