Water is the most crucial material for human survival, after air. Without water, life would not be possible. It is important to know how much water is available to us and how much water is polluted. We need to monitor pollutants vigorously, both at point and nonpoint sources, using advanced analytical techniques that can monitor ultra-trace amounts of contaminants. Water reclamation is an absolute necessity today because we have contaminated our surface water, and even groundwater in some cases, to a point that it is not clean enough for drinking or cooking. Most importantly, water must be used judiciously, and equal treatment must be paid to the reclamation and treatment of contaminated water. This book provides information on various global water challenges and solutions. We face many water challenges in terms of availability, quality, and sustainability (Chapter 1). There is an urgent need to find ways to make water more sustainable. To achieve this objective, we will have to address scientific, technical, economic, and social issues.