Water Facts - Worldwide Water Supply

Source: American River Water Education Center (ARWEC)


Water Facts

• Water covers about 71% of the earth's surface.
• 326 million cubic miles of water on the planet
• 97% of the earth's water is found in the oceans (too salty for drinking, growing crops, and most industrial uses except cooling).
• 3% of the earth's water is fresh.
• 2.5% of the earth's fresh water is unavailable: locked up in glaciers polar ice caps, atmosphere, and soil; highly polluted; or lies too far under the earth's surface to be extracted at an affordable cost.
• 0.5% of the earth's water is available fresh water.
• If the world's water supply were only 100 liters (26 gallons), our usable water supply of fresh water would be only about 0.003 liter (one-half teaspoon).
• In actuality, that amounts to an average of 8.4 million liters (2.2 million gallons) for each person on earth.
• This supply is continually collected, purified, and distributed in the natural hydrologic (water) cycle.

Where Water is Found and the Percentage

• Oceans - 97.2%
• Ice Caps/Glaciers - 2.0%
• Groundwater* - 0.62%
• Freshwater Lakes - 0.009%
• Inland seas/salt lakes - 0.008%
• Atmosphere - 0.001%
• Rivers - 0.0001%

If the Earth Were a Globe 28 Inches in Diameter:

• All of the water on the planet would fill less than one cup.
• Only 0.03% of one cup is in rivers and fresh water lakes.
• Slightly more than one drop of water would fill all the rivers and lakes.

Sources of Fresh Water

• Groundwater - water which infiltrates into the ground through porous materials deeper into the earth. It fills pores and fractures in layers of underground rock called aquifers. Some of this water lies too far under the earth's surface to be extracted at an affordable cost.
• Surface-water runoff - precipitation that does not infiltrate into the ground or return to the atmosphere: streams, rivers, lakes, wetlands, and reservoirs.
• Snow that is 4 inches (10cm) deep contains about the same amount of water as 1/3 inch (1 cm) of rain.