How much water does the world need to support growing human populations? What are the potential effects of climate change on the world's water resources? These questions and more are discussed in this thoroughly updated and expanded new edition. Written at the undergraduate level, this accessible textbook covers the fundamentals of water resources, water law, allocation, quality and quantity, health issues, and provides examples of potential personal actions and solutions. There is a keener focus on climate change, as many of the predictions made in the first edition have now come to pass. This new edition features improved artwork, more active learning prompts, more positive examples of beneficial changes, basic introductions to scientific approaches and a discussion of emerging contaminants and LiDAR technology. It contains strong teaching features, with new 'In Depth' and 'Think About It' sections to encourage class discussion, and homework questions to test students' understanding.