The sight of black, foaming, and stinking rivers is a familiar sight in urban India. We hear about the pollution of the Ganga and Yamuna rivers. Some may have also heard about certain (in) famous cases such as the Palar river in Tamil Nadu (polluted by tanneries), or the Tungabhadra river in Karnataka (polluted by a pulp and rayon factory), which are celebrated in the environmental literature for the social movements they sparked. The Central Pollution Control Board reported, in 2015, that 67% of the river stretches in its monitoring network are polluted.

Why is river pollution so ubiquitous in India? More than 35% of India’s 1.25 billion people live in urban areas. In the absence of infrastructure to treat wastewater, these urban centres let out untreated effluents into nearby rivers and lakes. Moreover, with industrialisation going hand-in-hand with urbanisation, and with the domestic use of industrial and chemical products increasing dramatically, pollution is no longer just biological in nature (i.e., sewage), but contains a variety of chemicals, including heavy metals.