The world is not only hungry, it is also thirsty for water. This may seem strange to you, since nearly 70 percent of the earth’s surface is covered with water. But about 97 pement of this huge amount is seawater, or salt water. Man can only drink and use the other 3 percent——the fresh water that comes from rivers, lakes, underground, and other sources.
The amount of fresh water will not be enough for us. First, we cannot use all of the fresh water, because some of it is in the form of icebergs and glaciers, or deep underground. Second, some of it is being polluted. Third, our need for water is increasing rapidly——almost day by day. Only if we take steps to deal with these problems now can we avoid a serious worldwide water shortage in the future.
One of the first steps we should take is to develop ways of reusing water. Today, in most large cities, water is used only once and then discharged into a sewer system. From there it goes to the sea or runs into underground storage tanks. But it is possible to pipe water that has been used to a purifying plant. There it can be used again. Another way is to make use of seawater by removing the salt. This is called desalinization, and it is already in use in many parts of the world.
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