The Urban Water Blueprint analyzes the state of water in more than 2,000 watersheds and 530 cities worldwide to provide science-based recommendations for natural infrastructure enhancements that can be integrated alongside traditional engineered solutions to improve water quality. This report addresses a critical issue facing mayors in cities around the world: access to clean and adequate water supplies. The growth of urban populations, coupled with incidences of sudden climate stress and long-term land degradation of drinking watersheds, pose increasing risks to urban water supply with serious implications for the future health and well-being of urban residents. Without water, cities cannot thrive.