The world’s rapid transition to urbanization contributes greatly to the pressure on water, food security, and energy, as the World Water Week Workshop on Securing Water and Food in an Urbanising World explored. We cannot simply look at urbanization as an urban problem. As Pay Drechsel from the International Water Management Institute stressed in the seminar, urbanization has strong links to rural and peri-urban areas, as urban centers become sinks for both rural-borne water and nutrients.
The informal sector around many rapidly developing cities, such as Chennai, has entered into a highly lucrative business pumping tanks and aquifers dry and selling the water to cities. The water is transported by trucks, adding energy costs to cities’ water supply. Through this system, informal water markets supply cities with every drop of water they can get, quickly drying up peri-urban areas. While it requires significant infrastructure costs to redirect water sources from increasing distances towards cities, peri-urban areas are suffering as cities squeeze them dry of water resources.
However, a current case in Bangalore shows that this situation can be partially remediated. Peri-urban areas may be able to swap high quality freshwater satisfying city demand for drinking water with treated wastewater fit for agriculture.
But who really wants wastewater? In Bangalore, the win has apparently been huge. The city constructed a 20km channel that directs wastewater out of the city and into its peri-urban areas. Over time, these areas that had run dry for over a decade began to see water in their tanks and wells again. It turns out that the wastewater, while moving out from the city, underwent different self-cleaning processes, and eventually infiltrated the ground, trickling back into wells and replenishing drinking water in peri-urban communities. These so far unknown opportunities have already resulted in conflicts for a resource whose value was so far underestimated.
In the Western World, we typically pay to have our wastewater taken away. But as the case in Bangalore shows, wastewater can be a valuable commodity that peri-urban areas may consider paying for in the future. Pay Drechsel is leading a team of researchers to look into the “water-swap” business model, which was recently also promoted by FAO (in its Water Report 35), where peri-urban areas support urban centers’ water demand and accept treated wastewater in return for agricultural production. The team will also look into how much peri-urban areas might be willing to pay to have cities redirect safe wastewater into their communities.