Irrigation is, and will remain, the largest single user of water, but its share of world water consumption is projected to decline from 80 percent in 1995 to 72 percent in 2025 under the business-as-usual scenario (BAU). Economic expansion, population growth and urbanisation will drive demand in the non-irrigation sectors including domestic, industrial and livestock water demand, which will increase by 62 percent over 1995 levels.
In developing countries, non-irrigation water demand will grow even faster, increasing 100 percent between 1995 and 2025. Irrigation water consumption will grow by only nine percent globally and 12 percent in developing countries because of limited growth in water supply and priority allocation for drinking water and industrial water uses. For the first time in world history, water demand for non-agricultural uses is growing more rapidly in absolute terms than water demand for agriculture. Compared with 1995, global water withdrawal in 2025 declines by three percent under the sustainable water use scenario (SUS) and by 36 percent under the water crisis scenario (CRI), according to IFPRI projections.
Growing water scarcity in response to rapid domestic and industrial water demand growth, particularly in the developing countries, is worsened by often severe constraints on the water supply. These constraints can be caused, first, by source limits — meaning absolute constraints on water supply — in some dry and highly developed regions including areas of northern China, northwestern India, the western United States, and much of West Asia and North Africa (WANA); and second, by economic constraints that slow the growth of new water supply infrastructure including dams and water distribution systems. These economic constraints are the result of the high financial, social and environmental costs of dams, irrigation infrastructure, and domestic and industrial water supply.
