The water often contains sewage, putting both the farmers and the people who buy their produce at risk of disease. But while the practice carries health risks, it also brings benefits to poor urban farmers and consumers who need cheap food, said the report by the International Water Management Institute (IWMI).

‘Farmers use wastewater because they have no choice,’ said IWMI researcher Liqa Raschid-Sally, who explained that this might be because of water scarcity or because traditional water sources have become polluted because they are so close to cities. After surveying 53 cities in developing countries in Asia, Africa and Latin America, the researchers found that more than 80 per cent of urban farmers in these cities were using untreated waste water.

However, banning the practice isn’t an option, said Raschid-Sally, as poor urban farmers don’t have an alternative source of water and the authorities don’t have the resources to enforce the laws if they were introduced.

‘Farmers normally know the risks and accept them due to the benefits they receive,’ said Raschid-Sally. But she added that consumers need to be made aware of the risk and taught how to wash vegetables properly. She also suggested that farmers could reduce the risks to their health by using alternative irrigation methods, such as not watering the leafy area of the crop, and storing waste water.

In several Asian countries, storing waste water is a common practice and allows faeces and harmful organisms to settle, which reduces the level of bacteria and worm eggs in the remaining water.

November 2008