The concept of sustainable development promotes a progress capable of satisfying the necessities of present and future generations; it is assumed that a sustainable management of water is still one of the problems to be solved in this century. This is the starting point of this book. Main political aspects are developed such as the EU Water Framework Directive, the globalization and privatization of fresh water, and the case of the new Australian structure for water regulation. A second part of the book is devoted to practical aspects including the effects of climate change and the implications of water sustainability on agriculture and cities, emphasizing the experience of the Environment Agency in UK.