Water is the source of all life on earth. The distribution of water, however, is quite varied; many locations have plenty of it while others have very little. Water exists on earth as a solid (ice), liquid or gas (water vapor). Oceans, rivers, clouds, and rain, all of which contain water, are in a frequent state of change (surface water evaporates, cloud water precipitates, rainfall infiltrates the ground, etc.). However, the total amount of the earth's water does not change. The circulation and conservation of earth's water is called the "hydrologic cycle."
(From the University of Illinois at Urbana-Champaign)
"He binds up the waters in his thick clouds, and the cloud is not split open under them."
"For he draws up the drops of water; they distill his mist in rain, which the skies pour down and drop on mankind abundantly. Can anyone understand the spreading of the clouds, the thunderings of his pavilion?"
"The wind blows to the south and goes around to the north; around and around goes the wind, and on its circuits the wind returns. All streams run to the sea, but the sea is not full; to the place where the streams flow, there they flow again."
"Who builds his upper chambers in the heavens and founds his vault upon the earth; who calls for the waters of the sea and pours them out upon the surface of the earth -- the Lord is his name."