The Delhi Jal Board’s (DJB) latest assessment has revealed that the volume of wastewater flowing into the Yamuna through the Capital’s 22 major drains is 76% higher than previously estimated, significantly raising the scale of the river’s pollution challenge.
According to government reports, the estimated discharge has increased from 750.4 million gallons per day (MGD) in May 2025 to 1,324.4 MGD in May 2026, following fresh surveys, drone mapping and volumetric studies conducted under the Yamuna rejuvenation project.
The revised figures indicate that Delhi may have been planning its river-cleaning efforts based on an incomplete understanding of the actual pollution load. Officials say the reassessment offers a more realistic baseline for expanding sewage treatment infrastructure, while environmental experts argue that restoring the Yamuna will require far more than additional treatment plants, including stronger interstate coordination and improved environmental flow in the river.
The findings also echo earlier concerns raised by the Comptroller and Auditor General (CAG), which warned that underestimating sewage generation could undermine effective remediation plans.
A Bigger Pollution Burden Emerges
The revised assessment paints a stark picture of the Yamuna’s most polluted stretch the 22-kilometre section between Wazirabad and Okhla which accounts for only around 2% of the river’s total length but contributes nearly three-fourths of its pollution load.
Among the 22 drains discharging into this stretch, the Najafgarh drain remains the largest contributor. Its estimated wastewater flow has nearly doubled, from 452.34 MGD to around 862 MGD, exceeding the combined treatment capacity of Delhi’s 37 sewage treatment plants (STPs), which currently stands at 814.23 MGD. Government officials said the updated estimates are based on comprehensive reassessment surveys and volumetric studies carried out over the past year to better understand untreated sewage entering the river.
Last year, Delhi Water Minister Parvesh Verma had announced that fresh mapping exercises, including drone surveys, were being undertaken to determine the actual sewage treatment capacity required for the Yamuna rejuvenation programme.
A senior government official also told Hindustan Times that while some drains have already been intercepted and diverted towards treatment plants, larger drains such as Najafgarh and Shahdara cannot be fully tapped using conventional methods. Instead, authorities are exploring decentralised sewage treatment plants for several sub-drains feeding these larger channels.
The official added that the Centre has set a target of increasing Delhi’s treatment capacity to 1,400 MGD, with upgrades to existing plants and new decentralised facilities already in various stages of planning and execution.
Beyond Treatment Plants
The latest findings have also revived broader questions about how Delhi has measured and managed sewage over the years. The CAG’s recent audit on the functioning of the Delhi Jal Board had concluded that the utility underestimated the city’s sewage generation, warning that realistic estimates were essential for preparing an effective treatment strategy.
The report also noted that although 56 new sewage treatment plants had been proposed under the Sewage Master Plan between 2017 and 2021, none were completed during that period. Environmental experts believe the revised estimates reinforce those concerns. Bhim Singh Rawat, coordinator of the South Asia Network on Dams, Rivers and People (SANDRP), said Delhi’s planning has relied on an oversimplified assumption that 80% of supplied water returns as wastewater, overlooking groundwater extraction and other local sources.
He also pointed to the growing volume of wastewater entering Delhi from expanding settlements in Haryana and Uttar Pradesh, arguing that the Yamuna’s restoration must be approached as an interstate challenge rather than a city-specific one. Rawat further stressed that sewage treatment plants alone cannot revive the river unless they are supported by greater environmental flow through additional releases from the Hathnikund Barrage and stronger coordination between state governments and the Centre.
The Delhi Jal Board and the Delhi water ministry did not issue an official response to requests for comment on the revised assessment at the time of publication.
The Logical Indian’s Perspective
The Yamuna’s condition has long symbolised the complexity of balancing rapid urbanisation with environmental responsibility. The Delhi Jal Board’s revised estimates suggest that the challenge may not simply be one of inadequate infrastructure, but also of planning based on incomplete information.
Accurate data is the foundation of sound public policy, particularly when the health of a river affects millions of people, biodiversity and the wider ecosystem.
Restoring the Yamuna will require transparent science, sustained investment, interstate cooperation and accountability that extends beyond electoral cycles. Rivers do not recognise administrative boundaries, and neither should the solutions designed to protect them.
As governments reassess the true scale of the problem, could this moment become an opportunity to build a more collaborative and evidence-based approach to river conservation across northern India?
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