The management of urban water systems has been a core responsibility of civil society throughout history. This reflects the central importance of these systems for human welfare and environmental protection. The current conventional approach to urban water management builds on well-established socio-technical systems that have evolved over the last century and have solved most of the water- and hygiene-related problems afflicting OECD countries in the past. These predominantly centralized and networked systems reliably treat and provide drinking water and safely transport, treat, and dispose wastewater. Challenges are posed, however, by population growth (both increases and decreases), climate change, emerging contaminants, as well as by the need to rehabilitate and replace aging infrastructure.
Though there is still an ongoing debate whether there is a need for new approaches in OECD countries, leading research institutes, international organizations and national governments are increasingly acknowledging that the conventional approach to urban water management cannot be the only solution for rapidly expanding cities in low- and middle-income countries in Africa, Asia and Latin America. With centralized and networked urban water systems out of reach for a large part of the global urban population, there is an urgent need for developing fundamentally new approaches, i.e. more flexible, cost-effective, resource-efficient non-grid systems that are able to cope with current and future urban water challenges.