Delhi's Sewage Treatment Plants Fail to Meet National Quality Norms

The Delhi government maintains that its sewage treatment plants (STPs) are operating at more than 88% capacity, suggesting most wastewater is being processed. Yet, analysis by the Delhi Pollution Control Committee (DPCC) paints a different picture: water discharged from the city’s plants continues to fall short of national quality norms. Of 17 drains carrying treated effluent, 16 showed pollutant levels above permissible limits. Tests revealed breaches across key parameters — pH, total suspended solids (TSS), chemical oxygen demand (COD), and biological oxygen demand (BOD). Elevated BOD, for example, reflects organic waste that depletes dissolved oxygen, threatening aquatic life. DPCC’s October report recorded severe exceedances, with BOD reaching 145 mg/l in the Sahibabad drain, 110 mg/l in Shahdara, and 60 mg/l in Najafgarh. COD levels also overshot safe limits, peaking at 296 mg/l in Shahdara and 152 mg/l in Najafgarh, compared with 50 mg/l standards. “Such high values, especially in a non-lean month, indicate that large amounts of untreated or poorly treated sewage are entering these drains, carrying organic waste and chemicals that the treatment system should have removed,” said Pankaj Kumar, aDelhi-based Yamuna activist.