At this very second, somewhere on the earth, water is falling as snow, rain or sleet. Despite this abundance, water does not fall evenly over the earth's surface. Where precipitation supplies too little water, the result can be desolation. Organisms in a dry environment must be specially adapted to minimize their need for water. Liquid water is the most important single substance for life on earth.
Some bacteria live without oxygen, but all known life forms require water.
Water makes up more than 7O percent of all living things. It is found in almost everything we see and touch. The use of water is required by almost every kind of economic activity. It is indispensable to our lives. Water is a natural resource that must be used wisely.