If you’re living in Delhi, you’re drinking uranium – and the government knows it

While Delhi’s smog dominates the winter headlines, an invisible poison is surging beneath the streets of a city that discusses its water crisis every year in familiar terms, from supply shortage to frothing.

Seven years after a landmark 2018 study by Duke University scholars, published in Environmental Science & Technology Letters, which first sounded the alarm on uranium contamination in the capital, with passing years, the crisis has transitioned from a scientific warning to a documented public health failure.

Last month, a new report from the Central Ground Water Board pointed to a sharp spike in uranium levels – nearly 13 to 15 percent of groundwater samples collected before and after the monsoon respectively, were found to contain higher traces of the element. In 2020, the figure stood at 11.7 percent.  

This is substantial considering that Delhi operates more than 5,500 tubewells and borewells, many of them in water-stressed and low-income areas. These wells tap shallow aquifers, the same type of aquifers which are flagged for uranium contamination in CGWB reports.

Regulation without response

Delhi now ranks third in India for uranium contamination in groundwater, trailing only Punjab and Haryana. Several other states have reported traces. Punjab was actually the first to report this contamination in the ’90s.

A review of central government groundwater reports shows a pattern. Uranium contamination in Delhi was first identified in pockets, but it has gradually spread across more districts and has crossed safety thresholds more frequently.

The Bureau of Indian Standards had codified a 30 ppb (parts per billion) safety limit in 2021 as per WHO norms. Until then, the country relied on a higher threshold recommended by the Atomic Energy Regulatory Board or AERB, which was 60 ppb. The change was significant because it acknowledged that uranium posed a public health risk even at lower concentrations.

However, activists and experts say even this standard is conservative.

According to Pankaj Kumar, an activist part of Earth Warriors, an NGO that works on groundwater and public health issues, countries like Australia cap uranium in drinking water at 15 ppb, reflecting a more precautionary approach. 

The government often points to its monitoring framework as evidence of action. The Standard Operating Procedure (SOP) on Groundwater Quality Monitoring lays out detailed sampling frequencies, parameters, and reporting mechanisms. Uranium is explicitly listed as a parameter under both “trend monitoring” (annual, pre- and post-monsoon) and “special purpose/new hotspot” studies.

Under the SOP, detection of high uranium levels is meant to trigger targeted studies, intensified sampling, and remedial planning. But across the CGWB annual groundwater quality reports and Delhi groundwater yearbooks reviewed for the years 2021-22, 2023-24 or the latest CGWB assessment do not contain any reference to any special purpose study initiated for uranium or any district level remediation plans.

Pointing to this inaction, Pankaj Kumar said that the critical issue is not only what the limit is, but how water exceeding it continues to be supplied. He pointed out that most of Delhi’s population does not drink bottled water and cannot afford household reverse osmosis systems, which are often presented as a solution. Even where ROs are used, they generate concentrated wastewater that is discharged into drains and eventually flows into the Yamuna, pushing the contamination elsewhere rather than resolving it.

Tankers, tubewells and unseen exposure

Delhi operates more than 5,500 tubewells and borewells, many of them in water-stressed and low-income areas. There is no public plan to shut these wells down, or retrofit them with Uranium Removal Units (URUs), or restrict their use based on contamination levels. Instead, water from these sources continuously goes into the city’s distribution ecosystem in two major ways.

First, through direct local use, where borewells supply homes, settlements, and institutions. Delhi has one of the lowest groundwater levels in the country, crossing the ‘over-exploited’ mark in 2024 and 2017, and was in proximity of the said mark in 2023 and 2020, according to the Reserve Bank of India Handbook of Statistics on Indian States, 2024-25.

Second, through water tankers, which are widely used in areas without reliable piped supply. Tankers are often presented by governments as an emergency service or welfare measure during shortages.

According to Pankaj Kumar, most tankers are filled at Delhi’s Water Treatment Plants (WTPs), but there is no mechanism at tanker filling points to test for uranium contamination. “Tankers are presented as a solution during shortages,” he said. “But the water being supplied is not screened for heavy metals like uranium.”

Government statements frequently highlight the number of tankers deployed during shortages. But they never clarify whether the water they deliver meets the same safety standards the government now recognises for drinkable water.

Problem that worsens quietly

One reason why uranium contamination has failed to trigger public outrage is its invisibility. There is no immediate illness, no smell, no change in water colour or taste. Kidney damage from chronic exposure builds slowly. By the time symptoms appear, tracing them back to water sources is nearly impossible.

Chronic ingestion of uranium in drinking water harms primarily through chemical toxicity, and not radioactivity which is a common misconception given the radioactive nature of uranium. Chemically, uranium is a heavy metal not just a radioactive element, and its main documented health impact is nephrotoxicity. In medical terms, nephro equals anything related to kidneys. The kidneys are the main target organ because they concentrate and excrete soluble uranium, which can injure renal tubular cells, and over time, reduce kidney function. 

Epidemiological and toxicological studies report associations between long-term exposure and markers of tubular dysfunction, higher microproteinuria - abnormal amounts of protein loss through urine which signals kidney damage, and subtle declines in renal function - especially where concentrations exceed guideline values.

Multiple international studies, including reviews cited by the World Health Organization, show that chronic exposure to elevated uranium levels in water can impair kidney function over time, even in the absence of immediate symptoms. 

Groundwater responsibility in Delhi is scattered across Union ministries, state agencies, utilities and households, until accountability is lost in the paperwork. There is no single office to confront, no clear failure to point to.

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