This is a century of urban transition. Today, well over 50 percent of the world iss population already lives in cities. It is estimated that by 2020, nearly 60 per cent of the worldsss population will live in urban areas, the growth predominantly taking place in developing countries and in peri-urban settlements housing the urban poor. This rapid and undirected urban growth has brought with it increased demand for basic services and poses three key challenges to sustainable urban development: the social challenge of equitable allocation among competing sectors, ensuring adequate access to safe water and basic sanitation by the urban poor; the environmental challenge of protecting freshwater sources from growing volumes of urban wastes; and the financing challenge of mobilizing resources to meet the growing cost of water provision from ever distant and degraded sources.
