How Much Water is There on Earth?

Where is Earth's Water?

Where is Earth

Earth's Water

The Water Cycle

The Water Cycle

The water cycle

Water Basics by Topic

Water Basics by Topic

Topics

Science Center Objects

The Earth is a watery place. But just how much water exists on, in, and above our planet? Read on to find out.

•  Water Science School HOME  •  Water Basics topics  •

How much water is there on, in, and above the Earth?

All Earth's water, liquid fresh water, and water in lakes and rivers

All water on Earth in a sphere, placed over a "dry" globe

Spheres showing:
(1) All water (largest sphere over western U.S., 860 miles in diameter)
(2) Fresh liquid water in the ground, lakes, swamps, and rivers (mid-sized sphere over Kentucky, 169.5 miles in diameter), and 
(3) Fresh-water lakes and rivers (smallest sphere over Georgia, 34.9 miles in diameter).

(Credit: Howard Perlman, USGS; globe illustration by Jack Cook, Woods Hole Oceanographic Institution (©); and Adam Nieman.)

The 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!

 

All Earth's water in a bubble

The globe illustration shows 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. This image attempts to show three dimensions, so each sphere represents "volume." The volume of the largest sphere, representing all water on, in, and above the Earth, would be about 332,500,000 cubic miles (mi3) (1,386,000,000 cubic kilometers (km3)), and be about 860 miles (about 1,385 kilometers) in diameter.

The smaller sphere over Kentucky represents Earth's liquid fresh water in groundwater, swamp water, rivers, and lakes. The volume of this sphere would be about 2,551,000 mi3(10,633,450 km3) and form a sphere about 169.5 miles (272.8 kilometers) in diameter. Yes, all of this water is fresh water, which we all need every day, but much of it is deep in the ground, unavailable to humans.

Do you notice the "tiny" bubble over Atlanta, Georgia? That one represents fresh water in all the lakes and rivers on the planet. Most of the water people and life on earth need every day comes from these surface-water sources. The volume of this sphere is about 22,339 mi3 (93,113 km3). The diameter of this sphere is about 34.9 miles (56.2 kilometers). Yes, Lake Michigan looks way bigger than this sphere, but you have to try to imagine a bubble almost 35 miles high—whereas the average depth of Lake Michigan is less than 300 feet (91 meters).

 

Water is on and in the Earth

The vast majority of water on the Earth's surface, over 96 percent, is saline water in the oceans. The freshwater resources, such as water falling from the skies and moving into streams, rivers, lakes, and groundwater, provide people with the water they need every day to live. Water sitting on the surface of the Earth is easy to visualize, and your view of the water cycle might be that rainfall fills up the rivers and lakes. But, the unseen water below our feet is critically important to life, also. How do you account for the flow in rivers after weeks without rain? In fact, how do you account for the water flowing down a driveway on a day when it didn't rain? The answer is that there is more to our water supply than just surface water, there is also plenty of water beneath our feet.

Even though you may only notice water on the Earth's surface, there is much more freshwater stored in the ground than there is in liquid form on the surface. In fact, some of the water you see flowing in rivers comes from seepage of groundwater into river beds. Water from precipitation continually seeps into the ground to recharge aquifers, while at the same time water in the ground continually recharges rivers through seepage.

Humans are happy this happens because we make use of both kinds of water. In the United States in 2010, we used about 275 billion gallons of surface water per day,and about 79.3 billion gallons of groundwater per day. Although surface water is used more to supply drinking water and to irrigate crops, groundwater is vital in that it not only helps to keep rivers and lakes full, it also provides water for people in places where visible water is scarce, such as in desert towns of the western United States. Without groundwater, people would be sand-surfing in Palm Springs, California instead of playing golf.

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 rivers and lakes. 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.

 

Where is Earth's water located?

For a detailed explanation of where Earth's water is, look at the data table below. Notice how of the world's total water supply of about 332.5 million mi3 of water, over 96 percent is saline. Of total freshwater, over 68 percent is locked up in ice and glaciers. Another 30 percent of freshwater is in the ground. Rivers are the source of most of the fresh surface water people use, but they only constitute about 300 mi3 (1,250 km3), about 1/10,000th of one percent of total water.
Note: Percentages may not sum to 100 percent due to rounding.

One estimate of global water distribution
(Percents are rounded, so will not add to 100)

Water source Water volume, in cubic miles Water volume, in cubic kilometers Percent of
freshwater
Percent of
total water
Oceans, Seas, & Bays 321,000,000 1,338,000,000 -- 96.54
Ice caps, Glaciers, & Permanent Snow 5,773,000 24,064,000 68.7 1.74
Groundwater 5,614,000 23,400,000 -- 1.69
    Fresh 2,526,000 10,530,000 30.1   0.76
    Saline 3,088,000 12,870,000 --   0.93
Soil Moisture 3,959 16,500 0.05 0.001
Ground Ice & Permafrost 71,970 300,000 0.86 0.022
Lakes 42,320 176,400 -- 0.013
    Fresh 21,830 91,000 0.26 0.007
    Saline 20,490 85,400 -- 0.006
Atmosphere 3,095 12,900 0.04 0.001
Swamp Water 2,752 11,470 0.03 0.0008
Rivers 509 2,120 0.006 0.0002
Biological Water 269 1,120 0.003 0.0001

Source: Igor Shiklomanov's chapter "World fresh water resources" in Peter H. Gleick (editor), 1993, Water in Crisis: A Guide to the World's Fresh Water Resources (Oxford University Press, New York).

 

Sources and more information: