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close this book Using water efficiently - Technological options
close this folder Water use efficiency
View the document What efficiency are we talking about?
View the document What are current levels of water use efficiency in irrigation?
View the document Factors affecting irrigation water use efficiency
View the document Water use efficiency in the urban sector: Definitions
View the document Factors affecting urban water use efficiency: Examples

Water use efficiency

In distinguishing among the three major water using sectors--agriculture, industry and domestic--the difference between consumptive and non-consumptive water uses is often neglected and the concepts are often misused. Unlike most resources, water can be used repeatedly at different times and locations. The following examples may help to distinguish between the two.

• Examples of consumptive uses are: evaporation losses from reservoirs and during crop irrigation; evapotranspiration through plants and vegetation in agriculture and green urban areas; evaporation from cooling processes and water used in industrial products (e.g. soft drinks and food processing); and the drinking of water.

• Examples of non-consumptive uses are: hydropower generation; recreation; fishing; navigation; washing processes in industry; and cleaning in domestic uses.

• Changes in water quality, such as the concentration of pollutants, temperature and salinity level, affect water availability. Therefore, water quality deterioration during non-consumptive use reduces the availability of water for consumptive uses.

• Water losses through soil percolation and seepage in agriculture, or in urban environmental uses such as public parks and gardening, and maintaining flows in streams, can be classified in either group. It depends upon whether the water lost in one use is reused somewhere else.