Download Is greywater safe for irrigation? - European Commission

17 June 2010
Is greywater safe for irrigation?
‘Greywater’ that is recycled from household washing can be used to irrigate home gardens,
according to a new study by Jordanian researchers. The researchers found that treatment units
supplied by the Jordanian government produced small quantities of recycled water that could be
used to irrigate gardens, whilst meeting national standards for irrigation of trees and many
home-grown crops.
Water is scarce across much of Europe, especially where summer temperatures are high, and methods for safely
recycling water are increasingly in demand. Last year, the European Environment Agency highlighted the problem
of water shortage in Europe and recommended that harvested rainwater and greywater from showers and kitchen
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sinks could be used for flushing toilets and watering gardens . In some countries, such practices are already
commonplace. In Jordan the government provided over 750 low-income households in 2003 with greywater
treatment units to help cope with water shortages.
However, the problem with greywater is that without proper treatment it may retain increased levels of elements
that are harmful to the soil and the crops or trees that grow in it. One particular concern is sodium, which in higher
concentrations can damage soil permeability and structure, ultimately reducing crop yields.
The researchers monitored sodium levels, as well as levels of other potentially damaging elements, to establish
whether water produced by the treatment units and used for irrigation was meeting Jordanian standards. The
results may be applicable to areas of Europe suffering from water shortage.
They found that the treated water complied with standards for irrigation of fodder crops and tree crops, including
olive trees. However, it did not meet standards for vegetables that must be cooked before eating. For these crops,
maximum allowable limits for suspended solids and nitrates are lower, and standards for other water quality
indicators are more difficult to meet.
Importantly, sodium levels were within the allowable limits, although the researchers did notice that concentrations
of sodium and organic matter increased over time. The leaves and fruits of olive trees were tested and were found
to have suffered no ill effects from recycled water. Olive trees are known to be able to tolerate slight increases in
salt, which the researchers say makes them suitable for greywater irrigation. Occasional leaching (deliberate
flushing) with fresh water may be a way to reduce build up of salts and organic matter in soils irrigated with
greywater, according to the researchers.
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EEA Report No 2/2009. 'Water resources across Europe - confronting water scarcity and drought'. Download from:
www.eea.europa.eu/publications/water-resources-across-europe
Source: Al-Hamaideh, H. and Bino, M. (2010). Effect of treated grey water reuse in irrigation on soil and plants. Desalination. 256: 115-119.
Contact: [email protected]
Theme(s): Agriculture, Water
Opinions expressed in this News Alert do not necessarily reflect those of the European Commission
To cite this article/service: "Science for Environment Policy": European Commission DG Environment News Alert Service, edited by
SCU, The University of the West of England, Bristol.
European Commission DG ENV
News Alert Issue 200
June 2010
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