There is one reality we are confronted with in almost all major Indian cities—the unmistakable, unshakeable stench of rotting sewage.
Year after year, Bengaluru’s lakes continue to froth angrily because of the high level of waste in them. But these lakes aren’t outliers. Like clockwork, every torrential monsoon in Mumbai sees the city’s roads flooded with sewer water. And in Delhi, the arterial Yamuna has been a cesspool for decades.
The cause for all this untreated sewage floating around is as obvious as it is revolting—sewage management in India is either non-existent or woefully unsatisfactory.
According to the Central Pollution Control Board’s (CPCB) estimates, the overwhelming majority—some 78%—of domestic sewage is left untreated in the country. It is either dumped into rivers and lakes or let out into fields, where it leaches into the soil, contaminating our groundwater. 70% of groundwater, according to the Composite Water Management Index, is already contaminated. At this rate, 21 Indian cities are well on their way to having no access to groundwater by 2020. (Read our story on India’s water scarcity problem)
India’s major cities are starved for clean water. Paradoxically, where clean water is scarce, the volume of sewage generated is growing unabated. In 2017, India’s class I and class II cities generated enough sewage to fill up 11,600 Olympic-size swimming pools daily—an estimated 29,129 million litres a day (MLD). In sharp contrast, the cumulative treatment capacity is a meagre 6,190 MLD. Over four times less than is needed. Even with another 1,742 MLD of sewage treatment capacity additions planned, the gap reduces by a mere 6%. According to the CPCB, this lack of treatment capacity has led to domestic sewage being the biggest polluter of our urban water resources.
All of this underlines an inarguable fact. Water runs in an unforgiving ecological loop. What you give is what you ultimately get back.
The root cause of this predicament are India’s centralised sewage treatment plants (STPs), which service most urban centres and provide reusable wastewater. And as urban populations continue to grow, the cracks in the system, long visible, are growing into gaping chasms.
Even where piped sewage networks exist, their patchy coverage across the city means that even the available capacity remains underutilised. “States like Tamil Nadu have spent a lot of money investing in a piped sewage network, but the volume of sewage flowing through them is very low,” says S.R. Ramanujam, a Mumbai-based water expert. As a result, only 33 of Tamil Nadu’s 73 sewage treatment plants are actually operational.
In light of all this, there is growing consensus that decentralised STPs are the way forward.