Additional surface-water deficit to meet global universal water accessibility by 2030

Abstract Universal access to safe drinking water for all is a key target of the United Nations Sustainable Development Goal 6. However, how water accessibility improvement impacts domestic water demand and surface-water deficit (the quantity of water demand that exceeds surface-water availability) are poorly known due to uncertainty and variability in domestic water use intensities (WUIdom). Here, we developed a data-driven model to create global gridded maps of historical and future WUIdom, constrained by 1758 survey-based records spanning 220 administrative units. The results show that water accessibility improvement dominated the growth in WUIdom over the period 1990–2015, particularly in developing and least-developed economies. Achieving universal water accessibility by 2030 may lead to an additional growth in global mean WUIdom by 21.7 L capita−1 day−1. Additional 88.3 million people, from 14 developing countries and 9 least-developed countries, may move into domestic surface-water deficit. Another 16% of global irrigated areas would be at risk of irrigation surface-water deficit mainly in South Asia, Central Asia, and North Africa. These findings imply the need of spatially flexible set of actions to achieve global universal water accessibility by 2030 without worsening surface-water deficit.