Coming Clean on Wastewater

By Mark Redwood

OTTAWA, Oct. 14 /CNW Telbec/ - Already home to more than half of humanity, cities are growing rapidly in the world's poorest countries. Amid food-price volatility and climate shocks, food production in and around these cities should be encouraged to meet the increasing demands.

But how are overstretched, congested cities, where land and safe water are in short supply, going to feed their expanding populations? By taking some simple, low-cost steps, wastewater can be part of the solution. These precautions include such innovations as inexpensive household filtration systems, protective clothing for farmers, as well as washing and disinfecting fruits and vegetables grown using wastewater.

There is growing recognition that the health risks of using wastewater to grow food can be managed, allowing poor countries to benefit from an abundant source of water. Viewing wastewater as a valuable resource rather than as a nuisance holds out real hope for improved food security in the developing world.

It is true that liquid waste from kitchens and latrines can contain intestinal parasites, chemicals toxins, and other serious threats to human health. But this wastewater also contains nutrients that help crops grow, and help growers save on fertilizer.

Farmers around the world already know this: an estimated 7 percent of farming worldwide relies on wastewater. Banning its use to protect public health, a common policy response, does not work. People who need food will grow it, irrigating their crops with whatever water they can find.

Newcomers to cities often end up in slums on the edges of cities, where some families are spending from 50 to 80 percent of their income on food. To meet their need for secure sources of food, they grow produce in backyards or on vacant public land. After feeding their families, they sell the rest, earning income that may fund their children's healthcare and education.

Urban agriculture is a major source of food and income in many parts of the world. Wastewater often makes it possible.

Water enters the food system at various points along the path "from farm to fork." In the past, the World Health Organization (WHO) focused on the water entering the system in farmers' fields, recommending that it should, of course, be high-quality.

Universal wastewater treatment remains the ultimate goal. However, large-scale water treatment is extremely expensive and currently not a realistic option for many low-income countries. But breakthrough research in Jordan, supported by Canada's International Development Research Centre (IDRC), has produced simple and cheap filtration systems that allow individual households to reuse wastewater they once poured down the drain.

In an important shift, the WHO issued new guidelines on wastewater use in 2006 that took local realities into account and focused on ways to minimize the health risks from wastewater. The major innovation of the new approach was to encourage relatively simple steps to protect health at all stages along the "farm to fork" chain.

In fields and city plots, for example, the best defence can be clothing that helps growers avoid direct contact with contaminated water. At city markets, taps with clean water can be provided so vendors can wash produce before selling it.

In homes and restaurants, fruits and vegetables can be soaked in an iodine, vinegar or lemon solution to reduce levels of bacteria and other pathogens. This is the last stage of a multi-barrier approach that seeks to protect consumers' health before food grown with wastewater reaches their plates.

The International Development Research Centre worked with the WHO on an information kit that presents the new wastewater guidelines in a clear and concise way, so they can be well understood by city governments and local health authorities. Researchers are now also field-testing the guidelines in Ghana, Senegal, and Jordan, making sure that these are feasible even where resources are limited. The findings will help to influence future WHO recommendations and government health policies - and to stop a valuable resource from going down the drain.

Mark Redwood leads IDRC's Urban Poverty and Environment program.

SOURCE International Development Research Centre

For further information: For further information: Ashifa Kassam, International Development Research Centre, Email:, Phone: (613) 696-2171

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