EARTH’S WATER

This article, written by the American Ground Water Trust was originally published in
THE AMERICAN WELL OWNER, 2002, Number 1]

HOW MUCH WATER IS ON THE EARTH

“Water, water everywhere nor any drop to drink”¹ was the likely cry of castaway sailors on the open ocean.  The salt water of the oceans makes up about 97.2 percent of all the water on the earth (total water volume: 1,357,506,000 cubic kilometers [km³]²), but cannot be used as a drinking water source without the removal of the dissolved salts it contains.  Frozen water in the ice caps and on the mountaintops of the world makes up 2.15 percent of the total water supply.  Fresh water comprises the remaining water resource (0.65 %). 

Ground water makes up 97.54 percent of the total fresh water supply (8,300,00 km³).  Water vapor in the atmosphere, soil moisture and seepage and surface water in lakes, rivers and streams comprise the remaining fresh water resource.  Half the ground water supply is estimated to lie below depths of one-half mile and is therefore not generally accessible as a source of drinking water.  Most private drinking water wells are less than 1,000 feet in depth. 

Although 8,300,00 km³ is a lot of water in the ground, it is not equally distributed around the world.  Many countries do not have adequate drinking supplies satisfactory means of protecting their water resources or educating their citizens about the threats to ground water quality.  According to the Water Health Organization (World Water Day Report – 2001), more than a billion people do not have access to safe drinking water because of polluted sources.  The table below provides some examples of the range of access:

Each of us is a steward of the world’s water resources.  We must take care to protect what we have where we find it so that the resource remains available and of good quality for today’s needs and for the generations to follow.

1)     “The Rime of the Ancient Mariner,” by Samuel Taylor Coleridge (1798).

2)     The water quantity information in this article is summarized from “The Water Encyclopedia,” (2^nd Edition 1990) published by Lewis Publishers, Chelsea, Michigan, USA.

[© American Ground Water Trust.  This article may be reprinted for non-commercial educational purposes provided it is used in its entirety and that reference is made to its source as an article in THE AMERICAN WELL OWNER, 2002, Number 1]