Water Pollution Trends in the Ganga: 2024 Report

The Ganga flows through 29 cities and supports 450 million people. CPCB monitoring shows BOD exceeding safe limits in 55% of monitored stretches. This is the definitive 2024 data report on where the river stands.

The Ganga is simultaneously India's most sacred river and one of its most polluted. For 450 million people — roughly one-third of India's population — the river is a source of drinking water, irrigation, livelihoods, and deep spiritual identity. Yet for most of its 2,525-kilometre journey from Gangotri to the Bay of Bengal, the river carries levels of pollution that make it unsafe for bathing, much less drinking, in multiple stretches.

Understanding the Key Pollution Metrics

BOD (Biochemical Oxygen Demand) measures the amount of oxygen microbes consume to break down organic matter in water. Clean water has BOD below 3 mg/L. Above 6 mg/L, most fish species die. Above 10 mg/L, water is effectively anaerobic and emits hydrogen sulphide (the rotten-egg smell associated with highly polluted river stretches near Kanpur and Varanasi). Faecal Coliform Count (FCC) measures sewage contamination — the safe limit for bathing is 500 MPN (Most Probable Number) per 100 mL; for drinking, it should be zero.

Ganga BOD Levels: Upstream to Downstream

The chart reveals a telling pattern: the river is relatively clean in its upper reaches (Gangotri to Haridwar), deteriorates severely through the UP industrial belt (Kanpur, Allahabad, Varanasi), partially recovers in Bihar (Patna benefits from cleaner tributaries like the Sone and Gandak), then worsens again approaching Kolkata. The worst single point in 2024 CPCB data is Kanpur Downstream at 9.8 mg/L BOD — three times the safe limit.

The Kanpur Problem: Leather Tanneries

Kanpur is home to approximately 400 leather tanneries — one of the highest concentrations in the world. The tanning process uses chromium sulphate as a preserving agent. Trivalent chromium Cr(III) from tannery effluent is relatively less toxic, but it oxidises in river sediment over time to hexavalent chromium Cr(VI) — a known carcinogen. Studies by the Indian Institute of Toxicology Research (IITR) Lucknow found Cr(VI) up to 190 μg/L in groundwater in Jajmau (Kanpur's tannery district), where the WHO safe limit is 50 μg/L.

CPCB monitoring data shows the most severe BOD and heavy metal contamination consistently appearing in the Kanpur-downstream to Allahabad stretch. Despite the construction of Common Effluent Treatment Plants (CETPs) under the Ganga Action Plan (1985) and Namami Gange, many tanneries continue to discharge partially treated or untreated effluent, particularly during monsoons when oversight is lower.

Sewage: The Bigger Problem

Industrial pollution is visible and relatively easy to point fingers at. Sewage is a far larger and more diffuse pollutant. The 29 cities on the Ganga generate approximately 11,765 MLD of sewage daily. The Sewage Treatment Plant (STP) capacity as of 2024 is about 6,700 MLD — a gap of over 5,000 MLD that flows directly into the river, carrying faecal coliforms, pharmaceuticals, hormones, and nutrients that drive algal blooms.

Namami Gange: What Has Been Achieved

Launched in 2015 with a ₹20,000 crore budget, Namami Gange is the most ambitious river cleanup programme India has undertaken. By 2024, 209 STPs with a combined capacity of 6,700 MLD have been built or are under construction. Over 10,000 km of drains have been tapped to prevent untreated sewage from reaching the river. 130+ ghats have been upgraded with faecal sludge management. Industrial effluent monitoring has been strengthened with online real-time effluent monitoring (OEMS) at 900+ large discharge points.

The results are measurable in some stretches. Haridwar's Har-ki-Pauri ghat — the most sacred bathing spot on the Ganga — now meets bathing quality standards 280 days of the year, compared to fewer than 60 days in 2014. The CPCB's 2024 report notes that BOD has improved at 46% of monitoring stations compared to 2014 baselines. Critically, dissolved oxygen — a key indicator of river health — has improved in the upper and middle Ganga.

But critics, including the National Mission for Clean Ganga's own expert panels, note that Varanasi, Kanpur, and the Bihar stretches remain far from target. Many newly built STPs underperform because municipalities haven't connected sewage networks to them. Political and industrial pressure has slowed enforcement of effluent discharge norms. River flow reduction (due to upstream irrigation diversions and dams) concentrates pollution and reduces dilution capacity.

“Building STPs is necessary but not sufficient. Until sewage networks are connected and industrial discharge is genuinely enforced, you are treating water in one place while more pollution enters from another.”

— Himanshu Thakkar, South Asia Network on Dams Rivers & People (SANDRP)

Related Articles

Water Quality

Water Quality Report: Mumbai

8 min

Water Quality

Borewell Water vs Municipal Water: What You Need to Know

8 min

Water Quality

Which Indian States Have the Best Water Quality?

8 min