Water use

Water use can mean the amount of water used by a household or a country, or the amount used for a given task or for the production of a given quantity of some product or crop, or the amount allocated for a particular purpose.

Globally, of precipitation falling on land each year (about 117,000 km (28,000 cu mi)), about 4 percent is used by rainfed agriculture and about half is subject to evaporation and transpiration in forests and other natural or quasi-natural landscapes. The remainder, which goes to groundwater replenishment and surface runoff, is sometimes called “total actual renewable freshwater resources”. Its magnitude was recently estimated at 52,579 km (12,614 cu mi)/year. It represents water that can be used either instream or after withdrawal from surface and groundwater sources. Of this remainder, about 3,918 km were withdrawn in 2007, of which 2,722 km (69 percent) were used by agriculture, and 734 km (19 percent) by other industry. Most agricultural use of withdrawn water is for irrigation, which uses about 5.1 percent of total actual renewable freshwater resources. World water use has been growing rapidly in the last hundred years (see graph from New Scientist article).