The world’s population is growing rapidly and concentrating in urban centres. This trend is particularly intense in developing countries, where an additional 2.1 billion people are expected to be living in cities by 2030. However, sanitation coverage (collection and treatment) is not keeping pace with urban growth and as a result most wastewater enters water courses untreated. Many farmers in developing countries grow crops, especially vegetables, in urban and peri-urban environments using this wastewater, raw or diluted, to irrigate their crops. Such wastewater is often heavily contaminated with disease causing organisms and chemical agents that can seriously harm the health of the farmers, the traders who handle crops and the people who consume them.

It is therefore very important for urban and peri-urban vegetable farmers to be aware of the health-risks associated with using wastewater for their irrigating crops and to know how to use wastewater safely at farm level to reduce those health risks.

Safe irrigation methods are essential when using wastewater for irrigation, but they need to be complemented with other practices from farm to fork to ensure the safety of others involved in the value chain. In 2006, the World Health Organization (WHO), together with the Food and Agriculture Organization of the United Nations (FAO) and the United Nations Environment Programme (UNEP), adopted a multiple-barrier approach to reduce the health risks to farmers and consumers posed by using wastewater in

agriculture. This approach opened the door to targeting a variety of entry points where health risks occur or can be mitigated before the food is consumed.

This second edition of the handbook focuses on low-cost and low-tech on-farm wastewater treatment and safe irrigation practices that farmers can adopt to grow safer products. When using the pronoun ‘you’, the handbook addresses extension officers, trainers of farmers, and farmers interested to apply and share new knowledge.

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