Access to safe water, sanitation and hygiene is one of the most basic human needs, and crucial for health and wellbeing. Progress in this field has hitherto been insufficient, and billions of people will still lack access to these basic services in 2030 unless progress quadruples in speed. Demand for water is rising due to rapid population growth, urbanization and increasing water needs from agriculture, industry and energy sectors. Decades of misuse, poor management, overextraction of groundwater and contamination of freshwater supplies have exacerbated water stress in many regions of the world. In addition, countries are facing growing challenges linked to degraded water-related ecosystems, water scarcity caused by climate change, underinvestment in water and sanitation, and insufficient cooperation on transboundary waters.