CREDIT: AP Photo/Brennan Linsley

Faulty casing and cementing in gas wells has contaminated drinking water in Texas and Pennsylvania, according to a new study.

The study, which was published in the Proceedings of the National Academy of Sciences but has not yet been made public, looked at cases of water contamination in drinking water wells in the two states and found that it was these casing and cementing failures — not the actual process of fracking — that are to blame for the contamination. Fracking involves drilling a deep well into the earth, then inserting a steel casing tube into the well and pumping cement into the well to seal the casing in place and, in theory, protect groundwater from the gas that travels through the tube to the surface. If that casing or cementing isn’t done correctly, however, it can lead to contamination, the study found.

“This is relatively good news because it means that most of the issues we have identified can potentially be avoided by future improvements in well integrity,” lead author Thomas Darrah from Ohio State University told the Dallas Morning News.

In other words, more thorough cementing and casing jobs could protect people who live near fracking wells from contamination.

“Many of the leaks probably occur when natural gas travels up the outside of the borehole, potentially even thousands of feet, and is released directly into drinking-water aquifers” Robert Poreda, another author of the study and professor at the University of Rochester said.

The researchers were able to trace where the methane that contaminated well water came from by tracking the noble gases — which don’t react with many other chemicals, and thus are easier to keep track of than some other gases — that are released with the methane.

This isn’t the first time contamination has been tied to faults in cementing and casing, rather than the actual act of drilling — including by leaders in the natural gas industry, who have struggled to assure the public of fracking’s safety amid reports of contamination and illness from people who live near fracking operations. In 2012, Mark Boling, executive vice president and general counsel of Southwestern Energy Co., said that the examples that he’s seen in Colorado and Pennsylvania where gas contaminated drinking water have all been “caused by a failure of the integrity of the well, and almost always it was the cement job.” The cementing and casing process is an essential part of any fracked well.

But anti-fracking activists say that cementing and casing are only part of fracking’s contamination problem. For one, there’s the issue of fracking waste: in 2012 alone, fracking wells in the U.S. created 280 billion gallons of toxic wastewater according to a 2013 report from Environment America. That wastewater often contains carcinogens and even radioactive materials, and the deep pits that the wastewater gets stored in are not foolproof. In New Mexico alone, the report states, chemicals from oil and gas waste pits have contaminated water sources at least 421 times.

And whether it’s the act of drilling itself or failures in casing or waste storage, contamination from fracking operations is a major problem in natural gas-heavy parts of the country. Last month, Pennsylvania made 243 cases of contamination of private drinking wells from oil and gas drilling operations public for the first time. West Virginia, too, has linked cases of well water contamination to oil and gas drilling. And this month, researchers at the University of Texas found that levels of arsenic, selenium and strontium were higher than the EPA’s limits in some private wells located within about 1.8 miles of natural gas wells.