Understanding   Water !
In the last decade of the 20th century alone, the earth's population increased by more than one billion people. At present rates, over the next 50 to 90 years the world's population will more than double. The demand on water supplies is growing exponentially. Clearly, understanding and using scarce water resources wisely is vital. Our very survival as a species depends on it.

As you no doubt learned in school, over two-thirds of the earth's surface is covered by water. But did you know that only about 2.8 percent of it is fresh water? And, more critically, did you know that only about 0.3 percent of the earth's total water supply is usable by humans?