Delhi’s groundwater contains dangerously high levels of uranium, lead, nitrate, and fluoride, with contamination intensifying between 2024 and 2025, the Central Ground Water Board’s annual report has revealed.
The survey, released in late November 2025, tested 83 to 86 locations across the capital. Results showed that roughly 13 to 15 per cent of samples contained uranium above the safe threshold of 30 parts per billion. About 24 samples breached this limit, ranking Delhi third nationally for uranium contamination after Punjab and Haryana.
Lead contamination proved even more severe. The CGWB report stated that Delhi registered the country’s highest proportion of lead-tainted groundwater during pre-monsoon testing, with 9.3 per cent of samples surpassing Bureau of Indian Standards limits. This far exceeded figures from Assam at 3.23 per cent and Rajasthan at 2.04 per cent.
According to health experts, lead acts as a neurotoxin that harms children’s cognitive development, raises blood pressure, damages kidneys, and carries carcinogenic risks. Authorities classify it as a probable human carcinogen with no safe exposure level.
The report documented worsening contamination trends. Nitrate violations climbed from 20.4 per cent of samples in 2024 to 33 samples in 2025. The CGWB traced this rise to farming practices, improper waste disposal, and sewage seepage into aquifers.
Medical literature links elevated nitrate in drinking water to methemoglobinemia in infants, a condition that drastically reduces the blood’s oxygen-carrying capacity. Adults face potential blood chemistry disruptions from chronic consumption.
Fluoride posed another concern, with exceedances rising from 16.5 per cent in 2024 to 17.78 per cent in 2025. The board noted that fluoride contamination stems largely from natural processes, as groundwater interacts with granite and similar rock formations deep underground. Prolonged intake can trigger fluorosis, weakening bones and joints while causing dental damage.
Salinity indicators showed sharp deterioration. Electrical conductivity, which measures dissolved salts and minerals, registered violations in 23.3 per cent of samples in 2024 before jumping to 33.33 per cent in 2025.
Delhi recorded particularly troubling figures for the Sodium Adsorption Ratio, a measure of water’s sodium content relative to calcium and magnesium. Some locations showed readings as high as 179.8, with 34.8 per cent of samples crossing acceptable limits. High SAR levels make water unsuitable even for industrial applications.
For Residual Sodium Carbonate, another salinity measure, Delhi led all Indian states with 51.11 per cent of samples exceeding the 2.5 meq/L threshold.
These findings carry immediate implications for public health. Approximately 5,500 tubewells across Delhi supply roughly 450 million litres of groundwater each day to residential areas, with many households depending entirely on borewells, tubewells, and hand pumps for drinking water.
Pankaj Kumar, a Delhi-based environmental activist, attributed the crisis to “over extraction of groundwater and boring activities”. He emphasised that the uranium levels, electrical conductivity readings, and SAR figures indicate water quality has deteriorated beyond safe use. “If SAR is too high, the water is not even good for industrial use, let alone other uses,” Kumar said.
Civil society group Earth Warrior responded to the report by writing to Lieutenant Governor V K Saxena and Chief Minister Rekha Gupta on Friday. The organisation demanded that Delhi Jal Board immediately release groundwater quality data for all operational tubewells and ranney wells.
The group’s letter highlighted that the board currently supplies over 450 million litres daily of untreated or minimally treated groundwater into local distribution networks, potentially exposing residents to fluorosis, methemoglobinemia, kidney damage, and carcinogenic substances.
The CGWB’s recommendations include protecting water sources, regulating fertiliser use in agriculture, deploying targeted treatment technologies, enforcing stricter controls on industrial waste discharge, and establishing continuous monitoring at contamination hotspots.
