The earth we live is a complicated place. The more you know it, the more you feel about it. The scientists use the term "Earth System Science" to describe the earth as the interaction of "Spheres" such as atmosphere, lithosphere, biosphere and hydrosphere. The book is to reveal how water resources distribute in the earth, where the drinking water comes from, how the climate influence our water resources under the situation fo global warming and which water purifying technologies the scientists are thinking.