Water is a precondition to life on Earth and is essential for sustainable development. Safe drinking water and sanitation are human rights.1 Water – including sanitation – is critical for socioeconomic development, food security and healthy ecosystems, and is vital for reducing the global burden of disease and improving the health, welfare and productivity of populations. The science is clear: the global climate change crisis is increasing variability in the water cycle, thus reducing the predictability of water availability and demand, affecting water quality, exacerbating water scarcity and threatening sustainable development worldwide. These impacts disproportionately affect poor and vulnerable communities and are compounded by contributing factors, including population increase, unmanaged migration, land-use change, reduced soil health, accelerated groundwater extraction, widespread ecological degradation and biodiversity loss.