Water pollution

Story hook

On the morning of 18 May 2024, a stretch of the Yamuna at Kalindi Kunj in south Delhi was covered in a three-foot blanket of toxic white foam. Devotees taking a ritual dip during the Chhath Puja preparations could not see the riverbed beneath their feet. The foam contained phosphates, surfactants, and faecal coliform counts of 2,40,000 MPN/100 ml — 48,000 times higher than the safe bathing standard of 5 MPN/100 ml. The Delhi Jal Board's emergency response was to deploy bamboo barricades + anti-foam defoamer chemicals before TV cameras arrived.

This was the fourth consecutive year Yamuna's foam had made national news. Despite Rs. 6,500 crore spent on the Yamuna Action Plan (1993-2015), 18 sewage treatment plants built by Delhi Jal Board, 22 drains in Delhi carrying untreated sewage (only 5 of 22 are intercepted), and the Supreme Court's December 2023 contempt notice to the Centre + Delhi government — the river remains biologically dead in the 22-km stretch from Wazirabad to Okhla. The BOD level peaked at 56 mg/L in 2024 (the safe limit for bathing is 3 mg/L); dissolved oxygen at Okhla fell to 0 mg/L — fish cannot survive there.

Meanwhile, 600 km upstream of Delhi, in Haridwar, the Ganga flowed clean enough to register DO of 8 mg/L and BOD of 1.5 mg/L at Har Ki Pauri (CPCB monitoring data, FY24). The Namami Gange Programme (Rs. 32,912 crore approved since 2014) had paid off in the upper stretches. 300 km downstream of Delhi, the Yamuna meets the Ganga at the Sangam in Prayagraj — and the combined river, despite a vast cleanup, struggles with iron, arsenic, fluoride contamination of groundwater that the Central Ground Water Board has mapped across 24 states.

This is the story of Indian water pollution: islands of progress (Namami Gange's upper Ganga) surrounded by widening damage (Yamuna, Hindon, Buddha Nullah, Vaigai, Hussain Sagar). And underneath it all, a slow-motion crisis of groundwater that is too deep, too distributed, and too cheap to mismanage.

Why this matters for UPSC

Water pollution is a frequent Prelims topic (asked 2017, 2018, 2020, 2021, 2022) and a regular Mains theme — every 2-3 years there's a question on river cleanup or groundwater. Prelims tests parameters (BOD, COD, DO, MPN), monitoring bodies (CPCB, CWC, CGWB), specific projects (Namami Gange, Yamuna Action Plan, JJM), and laws (Water Act 1974, EPA 1986). Mains probes the institutional gaps — why hasn't Rs. 30,000+ crore on Namami Gange cleaned the river completely?