The health risks associated with the use of wastewater for irrigation in developing countries

The IWMI (International Water Management Institute) studies the long-term benefits and/or disadvantages of using sewage and wastewater for irrigation, a common practice in the agriculture of developing countries, along with the possible solutions for reducing risks. The main study areas are Pakistan, Ghana, Vietnam and Mexico, countries in which the use of sewage and wastewater in agriculture is widespread.

The use of sewage and greywater for irrigation is a common practice in rural and peri-urban areas of developing countries. Wastewater is often the only source of water for irrigation in these areas. Even in places where other water sources exist, small farmers often prefer greywater because its high nutrient content reduces or even eliminates the need for expensive chemical fertilisers.

However, along with the short-term benefits, the practice also carries a number of health risks. As wastewater treatment is a process that only affluent countries can support, while it is prohibitively expensive in poorer countries, wastewater is used without treatment in those countries.

Thus greywater supports innumerable people particularly in Asia, Africa and Latin America, but dealing with the links connecting human health and the environment on the one hand and the reuse of wastewater on the other hand is of primary importance. However, terminating or over-regulating these practices should be avoided, because that could take away the only opportunity of income that many landless people have; while the risks do need to be carefully considered, the importance of this practice for the livelihoods of countless smallholders must also be taken into account.

The existing risks – such as the presence of carcinogenic heavy metals – must be recognised and the risks must be mitigated. The best example is introducing affordable, continuous monitoring in order to detect the presence of harmful contaminants in time. Of course, this also means that farming practices must be reformed, so as to introduce methods that reduce the risk of infection to a minimum in the interest of both farmers and consumers.



IWMI: Wastewater use for agriculture