Long-term water demand for electricity, industry and households

Better water demand projections are needed in order to better assess water scarcity. The focus in this paper is on non-agricultural water demand, as this is the fastest-growing and least well-modelled demand component. We describe an end use-oriented model for future water demand in the electricity, industry and municipal sectors, with several new features. In the electricity sector, effects of thermal efficiency improvements on water demand are incorporated in our model. In the industry and municipal sectors, we separately estimate potential water efficiency improvements for withdrawal and consumption, so that consumption is no longer a simple fraction of withdrawal. We develop three scenarios for 26 regions and the period 1971-2100. The Medium and High scenarios project increasing global withdrawal (1930-2876 km3/yr) and consumption (537-694 km3/yr) in 2100, with especially dramatic increases in developing regions. Also, an alternative future is presented, with high standards of living and much lower water withdrawal (1010 km3/yr) and consumption (236 km3/yr). Aggressive efficiency measures can reduce baseline withdrawal and consumption in 2100 by 60% relative to zero efficiency gains.