Water is (of course) the main part of the water cycle. As you can see in the picture, (ps thanks to osovo.com who owns this pic) water is what flows throughout the cycle.
The water plate is where the water sits under the earth
Because water cycles (gets recycled over & over again).
It warms it up to evaporate. It cools it down to condense it. It rains to precipitate. It flows off mountain, hills, Etc. to runoff.
It depend on were we are at in the water cycle