Although the U.S. Environmental Protection Agency determined hydraulic fracturing didn't contaminate private water wells in Dimock, Pa., the water there is probably not safe to drink, said Ron Bishop, a professor of chemistry at State University of N.Y. at Oneonta.

In fact, Bishop said he isn't sure the EPA is doing a good job educating the area's residents about the potential hazards present in their water.

Dimock, Pa., has been at the front line in the national debate on natural gas drilling through hydraulic fracturing, or fracking. The drilling technique calls for thousands, possibly millions of gallons of water to be pumped underground with toxic drilling chemicals and sand to fracture natural gas bearing rocks. The water that remains is a toxic sludge -- and a dozen households accuse local drillers of failing to properly clean their private wells after previously contaminating them.

Some area residents say their water looks like chocolate milk. Others have described the water as the color of milk and coffee.

The accusation has been the subject of several investigations by Cabot Oil & Gas Corp. (NYSE: COG), the Pennsylvania Department of Environmental Protection, and most recently the EPA. So far, all findings suggest the water is potable.

Federal regulators in March found traces of arsenic, sodium, methane, chromium and bacteria in the water but those levels were "within safe ranges," the EPA reported.

But Bishop said the levels of heavy metals and salts may not be what is most threatening to human health. He said he is wary of the EPA's declarative conclusions when federal regulators have yet to release their entire data.

Bishop Concerned About Methane

"What we have so far is still preliminary," Bishop said, who added he is convinced the methane present in some of the town's wells came from deep underground -- the natural gas that Cabot Oil is trying to harvest. "Out all the things that give me the most concern, it's the methane."

Methane's solubility with water changes as water gets heated. When water is cold, methane is more soluble and often times fully dissolved, but as water is heated, methane starts breaking off from the water molecules it was attached to, Bishop said. The change in water temperature does not have to be great for methane gas to start leeching from running hot water in either sinks and showers.

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Chemistry Prof Questions Safety Of Dimock, Pa. Water, Challenges EPA