"We found surprising levels of methane in home-owners' wells that were close to natural gas wells, " co-author Rob Jackson, Nicholas Professor of Global Change at Duke University, North Carolina, explained.
"We found that within a kilometre of an active gas well, you were much more likely to have high methane concentrations," he told BBC News.
The team from Duke University collected samples from 68 private water wells in the north-eastern states of Pennsylvania and New York.
"We found some extremely high concentrations of methane: 64 milligrams of methane per litre of drinking water, compared with a normal level of one milligram or lower," Professor Jackson observed.
Professor Jackson said he had witnessed contaminated water being set alight
"That sort of concentration is up at a level where people worry about an explosion hazard."
The BBC's Roger Harrabin shows how to get fuel from hard rock
Professor Jackson said that the simplest explanation of how the gas ended up in people's water supplies was down to "leaky gas well casings".
"If there are cracks or imperfections in the gas well, especially in the vertical section nearer the surface, then methane and possibly fracking fluid/waters," he said.
"That is the simplest and most likely explanation.
"There are other possibilities; some people have proposed that methane can migrate to the surface through fissures that are opened in process of fracturing the rock. To me, that is less likely."
Professor Jackson was keen to point out that the study's drinking water samples revealed no evidence of contamination from fracking fluids, of which about five million gallons are used to unlock the gas in each well.
The combination of rising energy prices and concern about future energy supplies has seen the technology being embraced by nations around the globe.
"Ten years ago, people did not really know about this source of gas," said Professor Jackson.
"The boom in the United States started in the Barnett Shale (found in Texas, and considered to be the largest onshore gas reserve in the US) and it has only been in recent years that we have realised how much gas is out there and economically available.
"it is the combination of energy economics and the emergence of new drilling and fracturing technologies that have made it cheap enough to do."
Sir, – Minister for Energy and Natural Resources Pat Rabbitte’s response to Fintan O’Toole’s article (August 16th) on our offshore licensing terms and his intention to issue new licences under the current licensing terms is disingenuous in the extreme (Opinion, August 18th).
But perhaps big oil’s biggest success was diminishing the political will to implement appropriate regulation. Even after the international community adopted the UN Framework Convention on Climate Change (UNFCCC) in 1992, the fossil-fuel industry managed to block meaningful progress — to the point that, if serious action is not taken soon, the entire process could unravel.
In Europe, Royal Dutch Shell’s lobbying so diluted the EU’s efforts that there are now no binding targets for renewables or energy efficiency for individual countries. The company even sent a letter to the European Commission’s president claiming that “gas is good for Europe.” Shell and other oil companies are now promising to work as “advisers” to national governments on how to deal with climate change.