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Yamuna's Pollution Load Underestimated: Delhi Drains Dump 76% More Wastewater
15 Jul
Summary
- Wastewater flow in 22 Delhi drains into Yamuna is 76% higher than estimated.
- Najafgarh drain alone dumps more wastewater than all STPs can treat.
- This 22-km Delhi stretch, 2% of Yamuna, causes 76% of its pollution.
A recent assessment by the Delhi Jal Board (DJB) has revealed that Delhi's 22 main drains are discharging 76% more wastewater into the Yamuna River than previously estimated. The revised figures, from 750.4 million gallons per day (mgd) to 1324.4 mgd between May 2025 and May 2026, highlight a significant underestimation of the pollution challenge.
The Najafgarh drain, identified as the largest contributor, is now estimated to dump approximately 862 mgd, exceeding the combined effluent treatment capacity of all 37 Sewage Treatment Plants (STPs) in Delhi, which stands at 814.226 mgd. This concentrated pollution from these drains, particularly Najafgarh, Shahdara, and Barapullah, is a major factor in the Yamuna's degraded state.
Officials indicate that a fresh assessment, including drone surveys and mapping, was conducted last year to understand the actual pollution load. While some smaller drains have been tapped and diverted to STPs, larger ones like Najafgarh and Shahdara pose technical challenges. The government is exploring decentralized STP solutions for sub-drains.
Experts emphasize the need for a scientific baseline for planning wastewater treatment facilities and addressing interstate water flow issues from Haryana and Uttar Pradesh. They also stress the importance of increasing the river's environmental flow, suggesting it be treated as an interstate project with central government involvement. The Comptroller and Auditor General (CAG) has previously flagged that DJB underestimated sewage generation, hindering effective remediation plans.
