Leachate, a toxic liquid produced when water passes through decomposing waste, can contaminate soil, groundwater, wetlands and farmland.
India's landfills face significant risks because much of the country's municipal waste is biodegradable and large quantities are dumped in open sites.
Studies at Delhi's Ghazipur landfill have detected hazardous substances, including cadmium, in groundwater at concentrations exceeding drinking water limits.
A September 2025 inspection of the Bandhwari landfill in Haryana found untreated leachate overflowing into plantation and forest areas, exposing gaps in collection and containment.
The article calls for modern, integrated treatment systems that account for changing leachate composition throughout a landfill's life cycle.
India’s landfill problem is often measured in tonnes of waste, but that captures only half the story. As rainwater and moisture move through layers of decomposing garbage, they pick up organic and inorganic pollutants, creating leachate. If not properly collected and treated, the toxic liquid can seep into soil and groundwater, altering their chemistry and carrying contaminants to wetlands and farmland.
The risks are particularly significant in a country where more than half the municipal waste is biodegradable and a large quantity is dumped in open landfills and wasteland. The question then arises: is India able to manage leachate effectively?
Before delving into experience across the country, let’s note the complex and changing nature of leachate. It forms as organic waste decomposes and oxygen is exhausted, triggering anaerobic processes that generate methane, volatile fatty acids and dissolved organic carbon. As water moves through waste it carries the compounds with ammonia, humic substances and heavy metals.
Young leachate has high levels of biodegradable organic pollutants, reflected in elevated chemical oxygen demand (COD) and bioch-emical oxygen demand (BOD). As the landfill ages, the BOD/COD ratio decreases. Mature leachate is characterised by relatively high ammoniacal nitrogen concen-trations and greater proportions of humic and other recalcitrant organic substances. The dissolved concentration and mobility of many heavy metals, including copper, zinc, lead, chromium and cadmium, generally decline with leachate maturation, but their persistence and mobility remain dependent on site-specific geochemical conditions, including pH and interactions with dissolved organic matter. At Delhi’s Ghazipur landfill, studies have already found hazardous substances and heavy metals like cadmium in ground-water at concentrations exceeding limits for drinking water.
The contaminant profile is also becoming more complex. Studies globally have shown presence of pharmaceutical products, micro-plastics and per- and polyfluoroalkyl substances (PFAS) in leachate. Pharmaceutical residues and biomedical waste may contribute to proliferation of antibiotic-resistant bacteria and resistance genes.
To assess whether the complex nature of leachate is recognised and contained in India, the authors of this article estimated leachate generation in the country. Using thumb rules cited in existing literature, the benchmark was set at a lower-threshold value of 50 litres of leachate per tonne of waste per day. The assessment indicates that major cities including Delhi, Mumbai, Hyderabad and Bengaluru likely generate high volumes of leachate given their massive daily waste generation and ageing landfills.
Next comes an analysis of collection and treatment systems. Here, cases suggest gaps even in con-ventional mechanisms. For example, at the Bandhwari landfill in Gurugram and Faridabad, a September 2025 inspection ordered by the National Green Tribunal (NGT) recorded untreated leachate overflowing into plantation and forest areas through temporary kutcha drains and concrete pipes. The site lacked gar-land drains (perimeter channels to intercept and divert surface run-off), and none of its three storage ponds had impervious lining. The leachate was reportedly transported to the Behrampur sewage treat-ment plant, but the quantity was lower than estimated generation. Similarly, in July 2025, NGT noted operational gaps at ...
This article was originally published in the October 1-15, 2026 print edition of Down To Earth