text: Proximity and access to water have been key factors in human settlement through history. Water, along with the spaces around it, create a potential for transport, trade, and power generation. They also provide the human population with resources like recreation and tourism in addition to drinking water and food. Many of the world's largest cities are located near water sources, and networks of urban "blue infrastructure", such as canals, harbors and so forth, have been constructed to capture the benefits and minimize risks. Globally, cities are facing severe water uncertainties such as floods, droughts, and upstream activities on trans-boundary rivers. The increasing pressure, intensity, and speed of urbanization has led to the disappearance of any visible form of water infrastructure in most cities. Urban coastal populations are growing, and many cities have seen an extensive post-industrial transformation of canals, riversides, docks, etc. following changes in global trading patterns. The potential implications of such waterside regeneration in terms of public health have only recently been scientifically investigated. A systematic review conducted in 2017 found consistent evidence of positive associations between exposure of people to blue space and mental health and physical activity.
  One-fifth of the world's population, 1.2 billion people, live in areas of water scarcity. Climate change and water-related disasters will place increasing demands on urban systems and will result in increased migration to urban areas. Cities require a very large input of freshwater and in turn have a huge impact on freshwater systems. Urban and industrial water use is projected to double by 2050.
  In 2010 the United Nations declared that access to clean water and sanitation is a human right. New solutions for improving the sustainability of cities are being explored. Good urban water management is complex and requires not only water and wastewater infrastructure, but also pollution control and flood prevention. It requires coordination across many sectors, and between different local authorities and changes in governance, that lead to more sustainable and equitable use of urban water resources.