Water is necessary for life. People can live only a few days (1) ________ it. Yet nearly 25 million people die each year because of it. Both industrial nations and developing countries are worried about (2) ____and quantity of water in the world.

Even though people, animals, agriculture, and industry use a lot of water, there is more than enough on the earth. Water covers about three-quarters of the Earth’s surface. However, 97.4 percent of it is salt water. Three-fourths of the Earth’s fresh water is frozen in glaciers and in the great polar ice caps. Most of the water we use (3) ________ from rivers, lakes, and the atmosphere. Less than one percent of the Earth’s water is usable, and we use it over and over again.

One of the (4) _______ about water is distribution. Water is not always distributed where the large (5) ________ centers are. Some regions get enough rain. But it is all in one or two short rainy seasons.