It is well known that nearly 75% of the earth surf-ace is covered with water, 
but about 97% of this huge amount is sea water or salt water. Man can only
drink and use the rest 3%, but most of it has been polluted.
There are many cities poor with water in the world. millions of people don’t
have enough water for drinking, many of them die because of lack of water .
there are many big factories . they put the dirty and poisonous water in the river.
It pollutes the river and makes people have many strange diseases.
Many people don’t know how to save water. They don’t turn off the tap
when they finish washing their hands in the public toilet. Because the water is free-paying.
Most of the students in the university use big basins of water to wash fruits .
