How much freshwater is there on Earth? Can science help us use water more efficiently? The 'Why Science Matters' series demonstrates how the science we learn at school is important in every aspect of our everyday lives. Using case studies and investigations, the series describes the development of science and technologies that can improve our lives – or lead to new scientific challenges and controversies. In 'Managing and Using Water', we find out about the most vital resource on Earth and how it shapes our landscape. We learn the importance of water as a solvent, how the power of flowing water can be harnessed to provide us with energy, how drinking water is cleaned and sewage treated, and new technologies to combat water shortages around the world.