Studies have shown that uranium-contaminated drinking water can cause severe health problems such as chronic kidney disease.
"Nearly a third of all water wells we tested in one state, Rajasthan, contained uranium levels that exceed the World Health Organization and US Environmental Protection Agency’s safe drinking water standards," said Professor Avner Vengosh.
Professor Vengosh, who researches geochemistry and water quality, said: "By analysing previous water quality studies, we also identified aquifers contaminated with similarly high levels of uranium in 26 other districts in northwestern India and nine districts in southern or southeastern India."
"Developing effective remediation technologies and preventive management practices should also be a priority."
They measured the isotope ratios in a number of the samples and compared them to data from 68 previous studies of groundwater geochemistry in 16 Indian states.
However human activities, especially groundwater being over-used for agricultural irrigation, may be contributing to the problem, said Ms Coyte.
India’s acquifers are mostly composed of clay, silt and gravel which have been carried down from the Himalayas by streams and uranium-rich granitic rocks.
When these acquifers are over-pumped, their water levels decline causing the minerals to oxidise and effectively enrich the uranium in the shallow groundwater that’s left behind.
"One of the takeaways of this study is that human activities can make a bad situation worse, but we could also make it better," Professor Vengosh said.
"Including a uranium standard in the Bureau of Indian Standards’ drinking water specification based on uranium’s kidney-harming effects, establishing monitoring systems to identify at-risk areas, and exploring new ways to prevent or treat uranium contamination will help ensure access to safe drinking water for tens of millions in India," he said.