"Water water everywhere, Nor any drop to drink" – The Rime of the Ancient Mariner by Samuel Taylor Coleridge

Did you know that more than 70 percent of the earth's surface is covered with water in places more than 6 miles deep? Did you also know that only 3 percent of the total water on earth is freshwater? That's right, 97 percent of all water is undrinkable salt water.

Of the 3 percent freshwater, slightly more than 2 percent is tied up in Antarctic ice or in the Greenland ice cap and, therefore, is unavailable.

This leaves slightly less than one percent of the total water on earth available for possible human and animal consumption and/or other uses.

Therefore, the words of the Ancient Mariner are nearly true and almost prophetic.

OK, a little more detail about freshwater. Of the one percent of freshwater on earth, one percent is surface water and 99 percent is groundwater.

Of the fresh surface water, 98 percent is found in lakes and swamps and two percent in rivers. Twenty percent of all fresh surface water worldwide is found in the Great Lakes.

This one percent freshwater should be adequate for all needs and uses on earth with the caveat that for human consumption, certain treatments such as filtration, clarification, and disinfection are required to make the water safe.

Unfortunately, the distribution of freshwater and the distribution of population do not always coincide. More than 800 million people worldwide lack access to safe freshwater sources. Moreover, in parts of the world, water treatments are unavailable.

Let's take a look at a few of water's physical and chemical properties.

Water is comprised of molecules each of which contains two atoms of hydrogen and one atom of oxygen.

Because of its unique configuration, water molecules attract each other which gives water a high surface tension.

Water is known as the "universal solvent" because it dissolves more substances than any other liquid.

Pure water is neutral. In chemical jargon, it has a pH of 7 which is neither acid (pH<7) nor alkaline (pH>7).

Water is the only natural substance whose three forms, solid (ice), liquid, and gas (steam) exist at temperatures found on earth.

Water is surprisingly heavy. One cubic foot of water weighs approximately 62 pounds.

Another interesting fact to consider: Water is directly or indirectly associated with every natural disaster on earth, hurricanes, tsunamis, tornadoes, volcanic eruptions, earthquakes, floods, droughts, you name it.

A final observation and a personal opinion:

Observation: Water is extraordinarily cheap, it is tremendously undervalued. Drinkable water delivered to your home costs much less than one cent per gallon, an amazing bargain.

Opinion: Which should be more valuable, water or oil? Answer: water. For humans, water is essential. With water, we live, without water, we die. The average life expectancy for a human in the complete absence of water is three days. We may not like it or be as comfortable, but we can live without oil.

In future columns, with this information as a background, I will elaborate on some of the above facts or explore interesting, contemporary, or controversial water issues.

Much of the above is adapted from the U. S. Geological Survey Publication, "Water Science for Schools", and from the "Encyclopedia of Climate and Weather", edited by S. H. Schneider.

Richard A. Engberg is Technical Director of the American Water Resources Association in Middleburg. He is a hydrologist with more than 45 years of experience, including 26 years with the U. S. Geological Survey, and 10 years as Manager of the National Irrigation Water Quality Program of the U. S. Department of the Interior, Washington, D.C.