M. Monto (sustainable technologies, Indian Institute of Science, Bangalore), L.S. Ganesh (management), and Koshy Varghese (civil engineering, both IIT Madras) explore the complex relationships between humans and water in an urban context, identifying fundamental issues within a framework of integrated models and simulations for sustainability assessment and forecasting. They write for students and researchers in environmental and urban studies, and for policy makers from the local to the international.