Cover Image
close this book Using water efficiently - Technological options
View the document Abstract
View the document Acknowledgements
View the document Foreword
View the document Introduction
View the document Sectoral water allocation in countries and regions
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
close this folder Measures to improve efficiency: Technological options
View the document Reducing seepage, leakage and percolation losses in irrigation
View the document Cost comparisons of sprinkler and drip systems
View the document Preventing evaporation and evapotranspiration losses
View the document Promoting water reuse
View the document Improvement of efficiency through better management
close this folder River basin management: When is low efficiency appropriate ?
View the document Basin water use efficiency
View the document Impact of increasing local WUE of a basin
View the document Technological, environmental and economic considerations
View the document Conclusions and policy recommendations
View the document References
View the document Annex I - Sectoral water allocation by country (145 countries)
View the document Annex II - Implications of increasing water use efficiency in a basin (a numeric example)
View the document Distributors of world bank publications

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.