Natural and built stores of freshwater are critical for both ecosystem vitality and societal development, enabling natural and human systems to cope with temporal variations in water supply and demand. For societies, the importance of water storage has grown as human population has increased and socioeconomic development has advanced. The significance of water storage will continue to grow as the impacts of climate change become more pronounced. In South Asia, as elsewhere, the capacity to store water is decreasing, even as the demand for water is rapidly increasing. Though largely unrecognized, declining water storage is a major contributor to local and regional water crises, ultimately threatening millions of people and many ecosystems throughout the region. In response to the burgeoning freshwater storage gap, the United States Department of State has funded the 3-year project titled Built Water Storage in South Asia to enhance water security in the region. This regional project – implemented by the International Water Management Institute (IWMI) in partnership with the Global Water Partnership South Asia (GWP SAS) – will contribute to a sustainable transformation in the way water storage is perceived, planned and managed. The project will be implemented in Bangladesh, Bhutan, India, Nepal and Pakistan.