Not Just High Uranium: Delhi's Groundwater Has More Toxic Chemicals, Says New Report

For decades, many of Delhi's households have relied on borewells, tubewells and hand-pumps for drinking water - water that often flows directly, with little treatment. This dependence underlines the importance of one simple fact: Clean groundwater means healthy people. Now, the latest water-quality survey by the Central Ground Water Board (CGWB), released in late 2025, has raised red flags for the capital. The report shows that 13-15% of groundwater samples from across Delhi had uranium above safe limits. But the alarm doesn't stop there. The same survey flagged other contaminants like nitrate, fluoride, lead, high salinity and elevated dissolved solids in a significant portion of wells.

Given the scale, with thousands of tubewells feeding households every day, these findings are cause for concern. Long-term exposure to multiple pollutants can harm kidneys, bones, development in children, even increase chronic disease risks. As environmental groups and public health experts insist, it is time for informed action through testing, treatment and transparency.

Here is a brief breakdown of what the CGWB report found, why each contaminant matters, and what you can do to protect your family.

What The CGWB Report Found: More Than Just Uranium

1. Uranium: A radioactive heavy metal with serious risks

According to the report, out of 83-86 tested locations in Delhi, 24 samples (roughly 13.35-15.66%) exceeded the permissible limit of 30 parts per billion (ppb) for uranium. This places Delhi among the worst-off regions in the country, behind only Punjab and Haryana, in terms of uranium contamination. Excess uranium in drinking water is known to damage kidneys, affect bone health, and over long periods may increase risks of certain cancers.

2. Nitrate: Invisible but risky, especially for infants

Many of the tested samples showed nitrate (NO3-) levels above safe limits. The CGWB and analysts say the contamination likely arises from agricultural fertiliser runoff, waste disposal and sewage infiltration, all too common in a crowded urban space.

High nitrate in drinking water can cause a condition called methemoglobinemia, or "blue baby syndrome," in infants, where blood oxygen capacity drops dangerously. For adults, chronic consumption may impact blood chemistry and carry long-term health concerns. 

3. Fluoride: Natural but harmful in excess

The report also found fluoride (F-) concentrations above safe limits in many samples. Unlike nitrate or uranium, fluoride contamination is often geogenic, meaning it comes from natural water-rock interactions deep in the aquifers, rather than human pollution. While low fluoride can help dental health, excessive fluoride over years can cause dental or skeletal fluorosis, weakening bones, damaging joints, and affecting teeth.

4. Lead: Neurotoxin, kidney-stress agent, hidden danger

Remarkably, the 2025 survey reports that Delhi had the highest share of lead-contaminated groundwater in India during pre-monsoon. 9.3% of samples exceeded safe limits. Lead is a potent neurotoxin. Long-term exposure can impair cognitive development in children, increase blood pressure, damage kidneys, and is classified as a probable human carcinogen, meaning there is no "safe" level of exposure.

5. Salinity, Dissolved Solids, Hardness: Water You Can Taste, But May Not Drink Safely

Many groundwater samples in Delhi showed high electrical conductivity (EC), a measure of dissolved salts and minerals. Around 23.3% of older samples (and increasing in the latest survey) exceeded EC limits, signalling high salinity, total dissolved solids (TDS), and water hardness.

Hard or saline water may not show dramatic "toxicity," but over time can stress kidneys, aggravate hypertension, increase dehydration risk, and make water unfit for cooking, especially for infants, elderly and chronically ill people.

Multiple Contaminants Means A Dangerous Mix

What makes the 2025 findings especially worrying is co-occurrence. Many wells do not have just one contaminant, but two, three or more. Imagine drinking water with elevated uranium, nitrate and lead, along with high mineral content. The combined effects may multiply risks like kidney stress, bone problems, developmental harm, even cancer over long periods.

Why Has This Happened: Causes Behind The Contamination

According to groundwater experts, environmental analysts and the CGWB itself, Delhi's groundwater troubles stem from a mix of natural geology, human activity, and over-extraction:

• Aquifer geology and natural rock-water interaction: Many aquifers in Delhi pass through mineral-rich rock layers. As water percolates through, it picks up uranium, fluoride and other naturally occurring elements.
• Over-extraction of groundwater: Excessive pumping has lowered the water table drastically. As a result, deeper aquifers, which are often richer in heavy metals and salts, are being tapped more heavily. This increases the chance of contaminants entering water supplies. 
• Pollution assimilation through fertilizers, sewage, waste seepage: Nitrate and lead contamination are often linked to fertilizer runoff, improper waste disposal, untreated sewage leaking into soil, or faulty sanitation. In a densely populated city, such pollution can seep into soil and reach aquifers over time.
• Salinity and mineral build-up due to natural salts and overuse, especially in arid or semi-arid zones. High salinity was found particularly in western and north-western parts of Delhi.

In short, it's a combined pressure, natural and man-made, that has turned many wells toxic.

What This Means for Delhi Residents: Health Risks And Who's Vulnerable

• Long-term kidney strain and cancer risk: Uranium and lead are heavy metals that accumulate slowly; long-term ingestion can lead to chronic kidney disease, weakened bones, and increased cancer risk.
• Child development concerns: Lead exposure affects brain development, IQ, behaviour. Elevated nitrate can also endanger infants (blue-baby syndrome). Fluoride excess can cause skeletal or dental issues.
• Adults with chronic diseases: People with kidney problems, hypertension, bone issues or compromised health face higher risks if exposed to multiple contaminants.
• General public health burden: Poor water quality can create a population-level burden of disease, kidney ailments, bone disorders, more chronic illnesses.

Given Delhi's reliance on tubewell and borewell water (for many, the only supply), the numbers affected could be large.

What You Should Do: Practical Steps For Safer Water Use

1. Get Your Water Tested Regularly

If you rely on well or tubewell water, get it tested. Many harmful contaminants (uranium, lead, nitrate, fluoride) are colourless and tasteless. Only lab testing will reveal them.

2. Use Proper Water Treatment Methods

• Reverse Osmosis (RO), Activated Carbon, De-ionization: This combined method is effective for removing heavy metals (uranium, lead), nitrates, salts and fluoride.
• Avoid reliance on simple filters or only chlorination: They don't remove heavy metals or dissolved salts.
• Change filters regularly and use certified cartridges designed to remove heavy metals.

3. Don't Drink Untreated Well Water, Until Safely Purified

Avoid using untreated tubewell or borewell water directly for drinking or cooking, especially for children, elderly or those with kidney or other health conditions.

4. Demand Transparency from Water Authorities

Understand which tubewells supply your neighbourhood. Demand that Delhi Jal Board (DJB) or local agencies publicly share latest water-quality test results (not older than 6 months). Civil-society groups are already calling for this.

5. Support Long-Term Solutions: Aquifer Management, Pollution Control, Recharge And Regulation

• Encourage local authorities to regulate groundwater extraction, recharge aquifers, reduce over-pumping.
• Push for proper waste disposal, sewage treatment and control of industrial or fertiliser runoff.
• Support environmental reforms to monitor and control heavy-metal contamination, land use and water-table management.

A Wake-Up Call for Delhi's Water Future

The CGWB's 2025 groundwater-quality report is more than a technical document, it is a warning siren for Delhi's residents. Uranium, nitrate, fluoride, lead, salinity, once scattered risks - are now converging in the city's aquifers. The fact that 13-15% of wells exceed safe uranium limits, and many more show dangerous levels of other toxins, should shift how we think about "tap water."

For thousands of households relying on tubewell and borewell water, an untreated, unfiltered supply, the risk is real. But the solution is within reach with regular testing, proper filtration, public transparency, and sustainable water management. Drinking water should nourish, not poison. With awareness, collective action and the right safeguards, Delhi can still ensure safe water for its people.

Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.