Check out this great illustration by the U.S. Geological Survey! Though our planet is blanketed in blue, were all its water collected, we would find that the total volume of freshwater available on earth is quite limited.
The largest sphere represents the total volume of freshwater on earth—in oceans, ice caps, lakes, rivers, groundwater, atmospheric water, and in all living creatures. This is equivalent to 332.5 million cubic miles of water or a sphere 860 miles in diameter.
The small sphere positioned over Kentucky represents the world’s liquid freshwater found in groundwater, lakes, swamps and rivers, equivalent to 2.55 million cubic miles, or a sphere almost 170 miles in diameter. Ninty-nine percent of this is groundwater, much of which is inaccessible.
The tiny bubble over Atlanta, Georgia, represents the freshwater in all the rivers and lakes on the planet—those places where we obtain freshwater to support life—or about 22,000 cubic miles, represented by a sphere just shy of 35 miles in diameter.
Credit: Howard Perlman, USGS; globe illustration by Jack Cook, Woods Hole Oceanographic Institution (©); Adam Nieman.
Data 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).