Water Pollution Crisis in Indian Cities: Rivers, Lakes and Treatment Challenges

India is home to some of the world’s most iconic rivers – the Ganga, the Yamuna, the Godavari, the Krishna – yet many of these water bodies are in serious ecological distress. Indian cities produce staggering volumes of sewage every day, but only a fraction of it gets treated before it enters rivers, lakes, and groundwater. The result is an urban water pollution crisis that affects public health, food security, aquatic ecosystems, and the economy. Let’s break down the numbers, the science behind water quality, and the regional patterns that define this crisis.

How much water does India actually have? 🔗

India receives roughly 4,000 billion cubic metres (bcm) of precipitation annually, including snowfall. Of this, less than half flows into rivers – estimated at about 1,869 bcm of surface water resources. However, only around 690 bcm of surface water can actually be put to use due to topographical limitations, uneven rainfall distribution, and lack of storage infrastructure. When groundwater (about 433 bcm of utilisable resources) is added, the total available water is still far short of what the country demands.

Water demand in India is heavily skewed. Agriculture accounts for the bulk of consumption – around 84% – followed by industry at roughly 12%, and domestic use at just 4%. This imbalance means that even small increases in industrial or domestic water demand put enormous pressure on an already stretched system. India currently has per capita freshwater availability of approximately 1,486 cubic metres per year, placing it in the “water stressed” category as defined by international standards (below 1,700 m³ per capita).

The sewage gap: generation versus treatment 🔗

This is where things get alarming. According to CPCB data from 2020-21, urban India generated 72,368 MLD (million litres per day) of sewage. The installed sewage treatment capacity stood at only 31,841 MLD, and the operational capacity was even lower at 26,869 MLD. In practice, only about 28% of urban sewage – roughly 20,236 MLD – actually received treatment, leaving 72% untreated and flowing directly into rivers, lakes, and aquifers.

To put it differently, Indian cities fill the equivalent of around 30,000 Olympic-size swimming pools daily with sewage , and most of it goes untreated into the environment. Between August 2022 and June 2024, sewage treatment capacity grew by only 545 MLD, while sewage generation increased by 788 MLD – the gap is actually widening, not closing.

Why do treatment plants underperform? 🔗

India doesn’t just have a capacity problem – it has an efficiency problem. According to the CPCB, fewer than half of India’s sewage treatment plants (STPs) work effectively. Many plants suffer from poor maintenance, intermittent electricity, outdated technology, and lack of skilled staff. In Delhi alone, only 14 of the city’s 37 STPs met revised effluent discharge standards in a 2024 review. Some plants release treated water with fecal coliform levels far above safe limits, effectively polluting the water they are supposed to clean.

Smaller cities and towns face even steeper challenges. Urban Local Bodies (ULBs) often lack the capacity to plan and implement wastewater management projects, and many are hampered by staff shortages, underfunded labs, and limited monitoring infrastructure. The result is a patchwork system where some cities have world-class facilities on paper but failing operations on the ground.

Understanding water quality indicators 🔗

How do we actually measure whether water is polluted? Scientists and regulators rely on three main categories of indicators.

Pathogen indicators: fecal and total coliforms 🔗

Coliform bacteria, particularly fecal coliform, serve as direct markers of sewage contamination. Their presence indicates that disease-causing organisms from human or animal waste have entered the water. Safe water should ideally have zero coliform content, and water must have coliform below 10,000 MPN per 100 mL to be considered safe for general human use. Many of India’s rivers far exceed these levels. For instance, the Delhi Pollution Control Committee’s monitoring found fecal coliform levels reaching 7.9 million units per 100 mL downstream on the Yamuna – thousands of times the permissible limit.

Biological and chemical oxygen demand (BOD and COD) 🔗

Biological Oxygen Demand (BOD) measures how much oxygen microorganisms consume while breaking down organic waste in water. A higher BOD means more organic pollution – essentially more sewage and biodegradable waste. Water with BOD between 1-2 mg/L is considered very clean, 3-8 mg/L is moderately clean, 8-20 mg/L is borderline, and anything above 20 mg/L is ecologically unsafe. For bathing, the CPCB standard requires BOD below 3 mg/L.

Chemical Oxygen Demand (COD) goes a step further – it measures all chemically oxidisable pollutants, including non-biodegradable industrial toxins. When COD is significantly higher than BOD, it points directly to chemical pollution from sources like tanneries, textile mills, and pharmaceutical plants. Both BOD and COD are expressed in milligrams per litre (mg/L).

Dissolved oxygen (DO) 🔗

Dissolved Oxygen is perhaps the most fundamental indicator – it tells us whether aquatic life can survive. For a river ecosystem to sustain itself, it needs a DO level of 6 mg/L and above, and fish require at least 4-5 mg/L. When organic pollution is high, microorganisms consume so much oxygen during decomposition that DO levels crash. In the most polluted stretches of Indian rivers, DO can drop to zero, creating biological dead zones where no aquatic life can survive.

Regional patterns: pollution doesn’t follow wealth 🔗

One might assume that richer states have cleaner rivers. The data tells a more complicated story. Research on river water pollution across Indian states shows that pollution levels don’t necessarily decrease with increasing per capita income.

States like Uttar Pradesh and Bihar consistently show some of the highest water pollution levels in the country, with BOD levels recorded between 60-100 mg/L and COD between 180-200 mg/L on certain river stretches. Both the Ganga and the Yamuna pass through these states and receive enormous loads of industrial waste and untreated domestic sewage. But wealthier states are not immune – Haryana and Delhi show very high pollution levels despite significantly higher per capita incomes.

Maharashtra leads the country with 54 polluted river stretches, driven by industrial corridors around Pune, Nashik, and Mumbai and textile manufacturing along tributaries of the Bhima and Godavari. Gujarat’s Sabarmati downstream of Ahmedabad, recording BOD levels of 292 mg/L, ranks as one of India’s most polluted river stretches. Even in the south, Chennai’s Cooum River has recorded BOD levels exceeding 345 mg/L, making it one of India’s most critically polluted waterways.

In contrast, southern and western states like Kerala, Karnataka, and Goa generally show low to medium pollution levels across their major rivers, though localised hotspots near cities and industrial areas exist. Rivers like the Narmada, Brahmaputra, and Beas have shown relatively low BOD values (under 6 mg/L) throughout their length.

Delhi and the Yamuna: a case study in urban river pollution 🔗

No discussion of India’s urban water crisis is complete without examining Delhi’s relationship with the Yamuna. The numbers here are staggering.

The 22-kilometre stretch of the Yamuna flowing through Delhi represents barely 2% of the river’s total length, yet it accounts for nearly 80% of the river’s total pollution load. Delhi’s approximately 20 million residents generate massive volumes of wastewater – the bulk from domestic sources and a significant portion from industrial activities including aluminium smelting, fertiliser production, iron and steel manufacturing, leather processing, pulp and paper, and dye manufacturing.

The Najafgarh drain, Delhi’s largest, carries approximately 65% of the city’s sewage. Combined with the Shahdara drain, these two channels account for roughly 84% of the Yamuna’s pollution within the capital. Despite having 37 STPs with capacity to treat over 80% of the city’s sewage, performance is dismal. Raw sewage continues to flow through 22 major drains directly into the river.

Decades of cleanup efforts with limited results 🔗

India has spent enormous sums trying to clean the Yamuna. The Yamuna Action Plan (YAP), launched in 1993 with support from JICA, has spanned three phases with investments running into thousands of crores. The broader Namami Gange Programme, launched in 2015, has sanctioned over 500 projects. Yet the river remains severely polluted.

BOD load in the Yamuna has actually increased from about 129 tonnes per day in 1982-83 to over 261 tonnes per day by 2019. The reasons, experts argue, are not primarily technical but stem from persistent governance failures – poorly maintained infrastructure, incomplete interception of drains, illegal dumping by sewage tankers, and the fundamental problem of treated and untreated sewage mixing in Delhi’s drainage system.

The national policy and regulatory landscape 🔗

India has a layered framework of laws and regulations targeting water pollution. The foundation is the Water (Prevention and Control of Pollution) Act of 1974, which established the CPCB and State Pollution Control Boards (SPCBs). A 2024 amendment bill introduced provisions to decriminalise several violations and impose monetary penalties instead, while also allowing the central government to exempt certain industrial categories from prior consent requirements.

Key national programmes include the Namami Gange Programme (with a budget exceeding ₹40,000 crore across its phases), the National River Conservation Plan (NRCP), and the Atal Mission for Rejuvenation and Urban Transformation (AMRUT 2.0). In October 2024, the Ministry of Environment, Forest, and Climate Change published draft rules for overhauling the Liquid Waste Management system, mandating wastewater reuse targets and establishing compliance frameworks for bulk water consumers.

However, implementation remains the critical bottleneck. Only 11 of India’s 28 states have wastewater reuse policies, and most lack clear action plans. Just 17% of treated wastewater meets CPCB standards for reuse. Multiple overlapping missions with differing timelines and targets add confusion at the ground level.

What needs to change? 🔗

The path forward requires action on multiple fronts simultaneously. First, the massive gap between sewage generation and treatment must be addressed through both scaling up capacity and ensuring existing STPs operate at full efficiency. Decentralised wastewater treatment systems offer a promising alternative for smaller towns that cannot afford large, centralised plants, though they require sustained financial support and local technical expertise.

Second, India needs to shift from viewing wastewater as waste to treating it as a resource. Organisations like the Centre for Science and Environment have advocated for a transition from a linear to a circular water economy , where treated wastewater is systematically reused for irrigation, industrial processes, and urban greening. Cities like Bengaluru, which already uses treated water for lake rejuvenation and groundwater recharge, offer early models of this approach.

Third, enforcement must be strengthened. New 2025 guidelines from MoEFCC now mandate minimum 500-metre separation distances between high-polluting industries and surface water bodies , but such regulations only matter if they are monitored and enforced consistently.

Finally, robust monitoring using modern technologies – including IoT-based smart water quality monitoring systems, GIS-based approaches for identifying pollution hotspots, and real-time data platforms – can greatly improve the ability to detect, trace, and respond to pollution events before they become irreversible.

What do you think? Can India realistically close the gap between sewage generation and treatment within the next decade, or does the solution lie more in decentralised systems and wastewater reuse? And should the “polluter pays” principle be more aggressively enforced against cities and industries that continue to dump untreated waste into rivers?

References

1. https://www.indiawaterportal.org/water-quality-and-pollution/pollution/water-pollution-in-india-a-comprehensive-overview
2. https://www.undp.org/india/when-yamunas-dead-fish-will-be-fresher
3. https://www.cseindia.org/brief-on-the-yamuna-what-ails-the-yamuna–11059
4. https://prsindia.org/billtrack/the-water-prevention-and-control-of-pollution-bill-2024