High levels of fluoride, nitrate in groundwater in Karnataka pose hazard to public health

It’s not just bottled water—naturally available groundwater in many parts of Karnataka is now proving to be hazardous to health. A recent survey conducted by the Groundwater Directorate has brought to light shocking findings: drinking water from over 450 groundwater sources across 23 districts in the state contains dangerously high levels of fluoride and nitrate.

These chemicals, when present beyond permissible limits, pose serious threats not just to human health but also to agriculture. Experts warn that the situation could worsen during the summer months.

According to the Permissible Limits of Indian Drinking Water Specification, drinking water should not contain more than 1 mg/litre of fluoride and 45 mg/litre of nitrate. However, most of the groundwater samples collected during the survey exceeded these limits.

Over 100 villages in 36 taluks across 13 districts were found to have fluoride concentrations above the safe limit. Additionally, more than 350 villages in over 100 taluks across 26 districts had nitrate levels beyond permissible limits.

Providing access to clean and safe drinking water for every citizen is a key goal under the Sustainable Development Goals – 2030, in which Karnataka has so far shown strong progress. However, the current state of groundwater contamination could obstruct the path toward achieving this objective.

Experts suggest that over-extraction of groundwater must be curbed, and sustainable recharge of water sources should be prioritized to prevent further damage.

What the data says

The survey involved testing over 2,000 groundwater samples across the state. Among 1,625 samples checked for fluoride, 98 showed levels exceeding the safety threshold. In the case of nitrate, 2,132 samples were tested, of which more than 350 had concentrations higher than acceptable.

This contamination was found not only in districts of North Karnataka but also in places like Kolar, Chikkaballapur, Bengaluru Urban, Shivamogga, and Mandya.

Why it matters

Nitrate contamination in drinking water can severely affect both health and the environment. It is particularly dangerous for infants, who may develop various health complications. Nitrate is also associated with allergies and fever-like symptoms. Fluoride, on the other hand, when present in excess, can lead to dental and bone-related issues, according to health experts.

Most affected areas

Raichur tops the list with 34 villages reporting fluoride contamination, followed by 18 villages in Kolar and 14 in Chitradurga. In Dinni village of Raichur taluk, the fluoride content was recorded at a dangerously high 3.43 mg/litre—over three times the permissible limit.

For nitrate, 45 villages in Belagavi, 29 in Koppal, and 27 in Kolar reported unsafe levels. The highest nitrate level was found in Bhanapur village of Koppal district, where it touched 65.57 mg/litre—well above the safe benchmark.

Ongoing monitoring and action

The Groundwater Directorate, in collaboration with institutions such as the Indian Institute of Science and a central government agency, continues to assess water quality across the state. According to Minister for Minor Irrigation N.S. Boseraju, the department is keeping a close watch and will take necessary action in areas where contamination has been detected.

Reported by Rafeeq Ahmad