East Calcutta Wetlands, India: integrating sanitation, engineering and ecology

The East Calcutta Wetlands are an indispensable heritage of the city of Calcutta, India, and globally recognised as a partly natural, partly man-made ecosystem that sets an example in sustainable wastewater reuse. The 2017 UN World Water Development Report emphasised the vital role of the East Calcutta Wetlands in treating the city’s municipal sewage through biological methods, without the aid of a mechanical sewage treatment plant but with the help of the community, whose livelihood is connected to this work. Considering that, globally, only 20% of wastewater is treated, the looming water crisis raging through many Indian cities, increasing calls for conservation and proper utilisation of water sources such as rivers and wise use of water/wastewater, it is relevant to examine the dynamics of these wetlands. They afford timely lessons for urban wastewater management and sustainability of a tropical city with ample sunshine. The wetlands are an outcome of engineering innovation connected to a drainage outfall system. This paper examines the context of that innovation and the lessons they hold out for the urban future.