This new edition of a well-established textbook covers the health, environmental, and engineering aspects of the management of rainwater and wastewater in areas of human development. Urban Drainage deals comprehensively not only with the design of new systems but also with the analysis and upgrading of existing infrastructure. Keeping its balance of principles, practice, and research , the fifth edition has had the most comprehensive update of any edition so far. It includes a new chapter on urban drainage planning, some significant restructuring of others and the introduction of new topics, including emerging contaminants, wastewater surveillance, AI, digital twins, and cyber-physical security. It also addresses current concerns about climate change impacts and intermittent wastewater pollution, and new ideas about sustainable and resilient systems. In all cases, the aim is to provide comprehensive, authoritative, and evidence-based content prioritising innovation, improved methods, and solutions. This is an essential text for undergraduates and graduate students, lecturers, and researchers in water engineering, environmental engineering, public health engineering, engineering hydrology, and related non-engineering disciplines. It also serves as a dependable and up-to-date reference for drainage engineers in water service providers, local authorities, and consulting engineers. Throughout the text, extensive examples are used to support and demonstrate the key issues.