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How much water is there on Earth?

How much water is there on Earth from the USGS Water Science School

How much water is there on Earth from the USGS Water Science School


How much water is there on (and in) the Earth? Here are some numbers you can think about:

  • If all of Earth's water (oceans, icecaps and glaciers, lakes, rivers, groundwater, and water in the atmosphere was put into a sphere, then the diameter of that water ball would be about 860 miles (about 1,385 kilometers), a bit more than the distance between Salt Lake City, Utah to Topeka, Kansas. The volume of all water would be about 332.5 million cubic miles (mi3), or 1,386 million cubic kilometers (km3). A cubic mile of water equals more than 1.1 trillion gallons. A cubic kilometer of water equals about 264 billion gallons.
  • About 3,100 mi3 (12,900 km3) of water, mostly in the form of water vapor, is in the atmosphere at any one time. If it all fell as precipitation at once, the Earth would be covered with only about 1 inch of water.
  • The 48 contiguous (lower 48 states) United States receives a total volume of about 4 mi3 (17.7 km3) of precipitation each day.
  • Each day, 280 mi3 (1,170 km3)of water evaporate or transpire into the atmosphere.
  • If all of the world's water was poured on the contiguous United States, it would cover the land to a depth of about 107 miles (145 kilometers).
  • Of the freshwater on Earth, much more is stored in the ground than is available in lakes and rivers. More than 2,000,000 mi3 (8,400,000 km3) of freshwater is stored in the Earth, most within one-half mile of the surface. But, if you really want to find freshwater, most is stored in the 7,000,000 mi3 (29,200,000 km3) of water found in glaciers and icecaps, mainly in the polar regions and in Greenland.

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There's way less water than I realized.

The images above show blue spheres representing relative amounts of Earth's water in comparison to the size of the Earth. Are you surprised that these water spheres look so small? They are only small in relation to the size of the Earth. These images attempt to show three dimensions, so each sphere represents "volume." They show that in comparison to the volume of the globe, the amount of water on the planet is very small. Oceans account for only a "thin film" of water on the surface.

Earth is a watery place. 

But just how much water exists on, in, and above our planet? About 71 percent of the Earth's surface is water-covered, and the oceans hold about 96.5 percent of all Earth's water. Water also exists in the air as water vapor, in rivers and lakes, in icecaps and glaciers, in the ground as soil moisture and in aquifers, and even in you and your dog.

Water is never sitting still. Thanks to the water cycle, our planet's water supply is constantly moving from one place to another and from one form to another. Things would get pretty stale without the water cycle!

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