South Asia is one of the most water-scarce regions of the world. The Himalayan river basins that supply much of the region’s water, traverse national boundaries and are under increasing pressure due to industrialisation, urbanisation and a rapidly-growing population. Water scarcity jeopardises food and energy security, both sectors being large water users. Sustainably managing these scarce water resources requires shared understanding and management in the context of the basin scale. It is critical to build will, integrated resource management capacity and cooperation, within and across the region. Currently, limited intra- and inter-country cooperation threatens the region’s ability to meet projected demand for resources and, in turn, its long-term economic growth and stability.