Tests show severe groundwater contamination around Delhi’s landfills

Samples taken at multiple distances showed extreme breaches in chlorine, hardness and fluoride, with results now forwarded to the Centre for review.

Groundwater aquifers around Delhi’s saturated landfill sites at Bhalswa, Ghazipur and Okhla are highly contaminated, with multiple parameters such as chlorine, sulphate, fluoride and hardness measuring several times higher than prescribed limits. This is based on an analysis of samples conducted by the Delhi government. Four samples were collected from varying distances around each dumpsite and tested across nine parameters. The results have been submitted to the central government and indicate heavy contamination caused by leachate from long-accumulated waste.

Activists warned the damage is irreversible and urged source segregation and proper leachate systems as biomining continues toward 2026 and 2027 targets. (HT ARchive)

Leachate is a toxic liquid formed when water percolates through waste in landfills. It dissolves chemical and organic compounds as it travels downward and can contaminate soil and groundwater if not collected or treated. The DPCC report accessed by HT shows significant breaches near the Bhalswa landfill. Total dissolved solids in groundwater near Bhalswa Janata Colony were nearly six times above standard levels. Chlorine levels were three times higher at 729 mg per litre against the 250 mg per litre limit. Hardness measured in terms of calcium carbonate was double the standard.

Chlorine levels, which should be below 250 mg per litre, reached 1269.6 mg per litre at Bhalswa Dairy, 869.7 mg per litre at Bhalswa Sanjay Gandhi Transport Nagar and 729.8 mg per litre at Janata Colony. Calcium carbonate limits were also breached in all samples. Transport Nagar recorded 784 mg per litre, and Bhalswa Dairy recorded 728 mg per litre. Fluoride levels exceeded permissible limits at Bhalswa Dairy. Nitrate levels remained within standards across Bhalswa locations.

Similar violations were observed around the Ghazipur landfill. Chlorine was recorded at 899.7 mg per litre near the fish market, 849.7 mg per litre near Ghazipur Dairy close to the mosque and 379 mg per litre near the dairy farms. Hardness through calcium carbonate, which should not exceed 200 mg per litre, was three times higher at Gazipur Dairy Farm in Gali Number 4 at 608 mg per litre and twice the limit at the fish market. Calcium and sulphate levels were within limits, but three of four samples breached the fluoride limit of 1 mg per litre. The maximum fluoride concentration of 1.66 mg per litre was found in a sample near the mosque in Ghazipur Dairy.

At the Okhla site in Southeast Delhi, four samples were collected. One location near the bus depot was dry. Water from the Delhi Jal Board booster pumping station met all standards. The other two samples from the Okhla landfill and BP Singh Camp violated most parameters. Chlorine levels at BP Singh Camp were the highest across all three landfills at 2169.3 mg per litre. Magnesium reached 176.98 mg per litre at BP Singh Camp and 171.14 mg per litre at the landfill site, far above the 30 mg per litre limit. Hardness in terms of calcium carbonate was 1216 mg per litre, which is six times higher than the standard of 200 mg per litre.

Activists warned the damage is irreversible and urged source segregation and proper leachate systems as biomining continues toward 2026 and 2027 targets. (HT)

All three landfill sites are oversaturated and operating far beyond capacity. Biomining of legacy waste is underway based on NGT orders, although the project has missed several deadlines. The latest deadlines for flattening the sites are by July 2026 for Okhla, December 2026 for Bhalswa and December 2027 for Ghazipur.

Environmental activist Diwan Singh, who led the Yamuna Satyagraha, said contamination of groundwater aquifers is irreversible. “Agencies can only focus on preventing further damage and expansion by laying systems for leachate collection and treatment. Over the last three decades, mixed waste, chemicals and industrial waste have been dumped on the landfills, especially in the initial period. They have been leaching slowly into the soil and water. This will further increase the problem in low-lying areas. The only long-term solution is minimising the damage and focusing on source segregation of waste to prevent further build-up,” he said. 

Independent environment and public health researcher Priti Mahesh said groundwater should ideally have been tested for heavy metals as well and warned that the detected parameters were already harmful. “Susceptible populations in particular are impacted. For instance, children and pregnant women may suffer if the nitrate levels are high. Similarly, magnesium and chlorine add hardness to the water, and it can impact those with kidney or heart problems. Such water around landfills is largely impacted by leaches and industrial run-offs and should not be used for drinking purposes,” she said.

An MCD official said that the process to remove the legacy waste is already being undertaken. “We are increasing the pace of the biomining. Bhalswa and Okhla landfill sites will be cleared in next few years however the Ghazipur waste volume is much larger. Meanwhile, we have taken several steps including setting up of drains along the periphery for collection of leachate which can be later treated. Once cleared, large parts of these landfill sites will be used for development of green belts,” the official added, requesting anonymity.