Increased urbanisation and water supply shortage have led urban and peri-urban farmers to reuse wastewater from urban centres that are often polluted with untreated municipal and industrial effluents. Localized sources of water, which include groundwater, streams, urban drains, piped water and (un)treated wastewater, in urban centres are likely to be severely contaminated due to the concentration of habitation. Untreated wastewater used for irrigation poses potential threat to health of both consumers and irrigators, and sanitation concerns need to be adequately addressed:
Using best practices for the safe use of wastewater and excreta;
Restricting the use of industrial effluents for irrigation;
Preventing contamination of crops with chemicals and or pathogens;
Preventing contamination of drinking water sources;
Reducing and eliminating use of pesticides; and
Managing water and crops to prevent expansion of vector borne diseases.
Wastewater treatment and reuse in agriculture may provide benefits to urban and peri-urban farmers in conserving fresh water resources, improving soil integrity, preventing discharge to surface waters, and improving economic efficiency. However, proper planning of wastewater collection and treatment systems are required, and some naturally-based treatment technologies can attain high levels of sanitary control for relatively low capital investment. Artificial or constructed wetland treatment system for confined space is one example that is ideal in the urban setting to remove nutrients with minimum energy requirements.
Ghana 2008 - Simple video clips created for information on safe vegetable production when water treatment facilities are not available in poor developing countries. The experience gained in Ghana was a joint WHO-IDRC-FAO project in applications of the WHO-FAO-UNEP Health Guidelines in the safe use of wastewater in agriculture: