Irrigation is the artificial application of water to the ground surface in addition to what falls naturally as rainfall.

Since the mid 1990s irrigation has consistently been the largest use for freshwater globally ⁽¹⁾.The use of recycled water for irrigation is widespread because water quality standards are less stringent where water is not for potable use or direct human contact. Irrigating land uses extensive amounts of water so there may be cost savings associated with using recycled water too. In the United States water used for irrigation represents 40% of all freshwater withdrawals and in 2000 amounted to 518 billion litres/day ⁽²⁾.

The two main irrigated environments are amenity/recreation areas (e.g. golf courses, public parks, and commercial landscaped gardens) and agricultural land (horticulture, crop production and grazing pasture for livestock).

The quality of water required for irrigation of agricultural land will depend on the crop type and whether the crop is eaten raw or cooked. In Australia recycled water is classified in one of four classes ranging from A - very high quality suitable for most purposes, through to D - lower quality water with more restricted uses. View a summary of the classification system.

Case Studies

Read about golf course irrigation in the UK and Florida, USA

Read about agricultural irrigation in Australia

References

(1) Environmental Performance Reviews: Water. Performance and Challenges in OECD Countries. (2003) Organisation for Economic Cooperation and Development.

(2) Hutson, S., Barber, N., Kenny, J et al (2004) Estimated Use of Water in the United States in 2000. U.S. Geological Survey

(3) Groves, S.J et al (2004) The use of non-potable water for crop irrigation, the microbiological risks of disease transfer to humans and the implications for agricultural water resources. In Proceedings of the 2^nd CIWEM National Conference Volume 1 (ed. N.J. Horan). p241-247

(4) Pescod, M.B (1992) Wastewater treatment and use in agriculture – paper 47. Food and Agriculture Organization of the United Nations.