Protecting water is everyone’s responsibility, and it should be a priority in national policies, as well as the subject of debates for national and international organizations. This book, by the Institute of Environmental Law and Sustainability of the Catholic University of Salta (Argentina), aims at making a significant contribution to face this vital crisis our century is going through. The content of this book can be summarized in the words of Néstor Cafferatta: “Without water, the world is unsustainable”. This volume introduces different perspectives on the importance of water for all living beings, for the preservation of nature as a whole, and for the safety of the environment. On the other hand, it claims that the availability of “safe” or drinking water is a human right, since people’s quality of life, living standards, health, well-being, and the development depend on it. In this context, Graciela Ayala Flores states that “Water springs as the biggest geopolitical conflict in the 21st century, since it is expected that, by 2025, water demand, vital for human life, will exceed water supply by 56 %.”