Someone suggested the water was acting as a lubricant.

The water then acts like a lubrication between the individual molecules.

Sooner or later water must have acted as a transporter for dissolved materials.

Consequently, in this case, the water is acting like an acid since it supplies a proton.

Upon exposure to high humidity, however, water goes into the hair fiber, acts on the proteins, and lets them change back.

In reality, pure water rarely acts as a H donor.

Hot water acts as insulation and almost invariably keeps the cake from cracking.

At these wavelengths, however, water in the clouds acts as an efficient absorber.

The water acts like acid on the alien's skin.

In the pools the water cools the fuel and acts as a radiation shield.