Nelly Bassily | August 25, 2008
Though the use of wastewater in urban agriculture can be harmful to human health, Liqa Raschid-Sally of the International Water Management Institute (IWMI) and principal author of the recently-published study says that its use should not be banned. If this were to happen, some vegetables would become inaccessible in cities. Ms. Raschid-Sally states that 75 per cent of cities are supplied with vegetables grown in urban or peri-urban areas and irrigated by wastewater. To see the full IWMI report, Comprehensive Assessment of water management in agriculture, visit: http://www.iwmi.cgiar.org/SWW2008/PDF/CA_53_city_Final_August_2008_V5.pdf.
Wastewater is any water that has been altered through human activity, whether through domestic, industrial, agricultural, or other use. Some types of wastewater are more harmful than others. Wastewater is separated into two categories: blackwater and greywater. Blackwater contains many pollutants or substances that are difficult to eliminate such as cosmetics, fecal matter, and industrial byproducts. This water typically presents the greatest danger to human health since, in most African cities, it is not treated before being used on vegetable crops. Greywater is considered more acceptable for agricultural use. This type of water has been used in the home, usually for washing dishes, bathing, or showering, and contains far fewer pollutants.
Here are some additional resources on wastewater and safer ways to use it:
-The World Health Organization Guidelines for the Safe Use of Wastewater, Excreta and Greywater: http://whqlibdoc.who.int/publications/2006/9241546832_eng.pdf
-A study on Irrigated Urban Vegetable Production in Ghana, its characteristics, benefits, and risks: http://www.cityfarmer.org/GhanaIrrigateVegis.html
-A video on safer use of wastewater in urban agriculture, entitled Recycling Realities in African Cities: Towards safe wastewater use in agriculture: http://www.youtube.com/watch?v=s17_35B7SdY
-An audio report by the Canadian Broadcasting Corporation on the food crisis and the use of wastewater in urban agriculture in Uganda and Ghana: http://www.cityfarmer.info/cbcs-dispatches-reports-on-food-crisis-city-farming-uganda-ghana/
You may also wish to consult the following Farm Radio International scripts and news stories on urban agriculture and best practices for using wastewater:
–“Urban agriculture provides relief from high food prices” (FRW#23, June 2008):
–“Garden on your rooftop” (Package 39, Script 2, April 1996)
–“Grow vegetable vines in small spaces” (Package 39, Script 1, April 1996)
–“Gardening in tires” (Package 41, Script 5, July 1996)
–“Reduce lead in city gardens” (Package 41, Script 2, July 1996)
–“Garden while you shower” (Package 54, Script 3, January 2000)
–“Use moringa seeds to clean dirty or polluted water” (Package 54, Script 11, January 2000)
–“Growing vegetables when water is scarce” (Package 45, Script 7, July 1997)
Finally, here are some questions that may help if you choose to research the use of wastewater in urban agriculture in your area:
-What sorts of fruits and vegetables are grown in your city?
-Where do the urban farmers get the water for their crops? Do they know if the water is safe for this use? How do they determine its safety?
-In the face of growing water shortages, what methods do urban farmers in your area use to ensure their supply of water for irrigation?