Book excerpt: This book introduces the readers to possible aspects of the rainwater harvesting system against urbanization to plan, design, and implement. Practical applications of rainwater harvesting to supplement potable water, stormwater management, greywater reuse, and managed aquifer recharge are included. Along with conventional practices, advanced technologies for conceptualizing, data collection and processing, test procedures, and design principles are provided to illustrate the theory. This book is a pathway to a water smart city, example problems reflect the solutions for harvested water quantity and/or quality and afterward. Socio-economic assessments are incorporated to explore comprehensive knowledge. The book covers an interdisciplinary field, thus, suitable for students, researchers, and professionals associated with rainwater harvesting system development and management