Researchers who tested 91 private water wells and springs in southwestern Pennsylvania found that samples closer to natural gas operations tended to contain more salt, and that higher salinity correlated with higher radium levels, a naturally occurring radioactive element linked to increased cancer risk at elevated exposure.
They also found something that goes hand in hand: every radium measurement in the study remained within the Environmental Protection Agency's legal limits. Not one sample exceeded the federal drinking water standard.
Both facts are true, and holding them together is the point. The Penn State team that ran the study described the answer to whether fracking raises radium levels in drinking water as not a simple yes-or-no.
The Chemistry That Connects Salt to Radium
Radium exists at very low concentrations in soil and rock nearly everywhere. It generally stays bound to the rock rather than dissolving into groundwater.
Salt changes that. When salty water moves through an aquifer, dissolved ions can displace radium from the surrounding rock and push it into the freshwater a household draws from. This is why salinity is the variable researchers watch. It functions as a lever on radium mobility.
Nathaniel Warner, an associate professor of environmental engineering at Penn State, explained why radium matters biologically. Because radium behaves chemically like calcium, the body routes it toward bone. Over time, Warner said, "that radium will decay, releasing particles and energy that will damage your cells."
The team sampled homes at roughly half a mile, just under two miles, and slightly more than three miles from unconventional oil and gas operations. Crucially, they tapped wells before any household treatment system, so the results describe raw groundwater rather than what comes out of a filtered tap.
The Findings Are Narrower Than the Headline Suggests
Of the 91 samples, six could potentially be associated with fracking wastewater. The researchers framed this as evidence that spills or mismanagement could produce localized impacts rather than a broad effect generalizable across all extraction operations.
Samples taken within about two miles of operations were more likely to show elevated radium levels, but the study reported that this pattern was not strong enough to be cited as a broad correlation.
And the salinity itself has many possible origins. Warner noted that road salt, nearby septic tanks, and even animal waste can all raise salinity in an area. That means the study cannot isolate drilling as the cause of the measured salinity, which in turn limits what can be concluded about drilling and radium.
Prior work from another Penn State team had identified elevated salt hotspots near unconventional operations in the Northern Appalachian Basin. According to Warner, areas of elevated salinity can carry up to 200 percent higher risk for radium-related health effects. That figure describes relative risk in higher-salinity areas, not the measured risk in these 91 homes, where radium levels remained below federal limits.
The study appeared in Environmental Science and Technology and was supported by the Health Effects Institute and the US National Science Foundation. Co-authors came from Penn State, Syracuse University, Juniata College and the University of Minnesota.
Private Well Owners Are the Group with Something to Do
Pennsylvania ranks second in US natural gas production, accounting for about one-fifth of national output in 2024. It also has a large population on private wells, and that combination defines who should pay attention.
Households on public water systems are already covered by federal radium testing requirements under EPA drinking water rules. Private well owners are not, which leaves testing entirely to the homeowner.
Well owners in Washington and Greene counties, and in other areas with drilling activity, can ask a state-accredited laboratory to test for radium-226 and radium-228 along with basic salinity indicators such as chloride and total dissolved solids. Testing salinity first is often the cheaper screening step, since elevated salt is the signal that makes radium testing worthwhile. The EPA's radionuclides in drinking water rule explains the standard against which those results are measured.
County conservation districts and Penn State Extension water resources programs can point residents toward accredited labs and help explain results.
Households that already have a treatment system should know that not all filters remove radium. Reverse osmosis and ion exchange systems are generally effective, whereas standard carbon filters are not designed for this purpose. Homeowners considering treatment should test first, because installing equipment without knowing what is in the water can mean paying for a system that addresses the wrong problem.
Renters on private well water have less control but can ask a landlord for recent test results.
Where the Science Goes from Here
The researchers were explicit that more work is needed. They plan to continue with larger samples and more targeted sampling near oil wells, and to extend the search to abandoned oil and gas wells across the region to assess how historical drilling affects communities today.
The study also cannot address a question many households care about most, which is whether long-term exposure at levels below the federal limit carries meaningful risk. That is a broader scientific debate the study was not designed to settle.
For now, the reasonable posture is neither alarm nor dismissal. Every sample in this study met federal standards. A small number showed a possible fingerprint of drilling wastewater. Salinity remains the practical variable a homeowner can screen for, and testing is the only way to know what is in a private well.
Residents with specific health concerns about their water should speak with a clinician and their county health department rather than relying on either industry or advocacy framing of the findings.
Key Questions Answered
What did the study find? Samples taken closer to gas operations tended to have higher salt concentrations, and higher salinity tracked with higher radium. Six of 91 samples could potentially be associated with fracking wastewater.
Was any water unsafe to drink? All radium levels in the study remained within the Environmental Protection Agency's legal limits. No sample exceeded the federal standard.
Why does salt matter for radium? Salty water can displace radium from surrounding rock and move it into groundwater. Salinity acts as a lever on how much radium ends up dissolved in well water.
Does this prove drilling caused the contamination? No. The researchers noted that salinity can also come from road salt, septic tanks, and animal waste, and that the correlation is not broadly generalizable to all extraction operations.
Who should consider testing their water? Private well owners, particularly in areas with drilling activity. Private wells are not covered by federal drinking water testing requirements, so testing is the homeowner's responsibility.
What test should be requested? A state-accredited laboratory can test for radium-226 and radium-228 along with chloride and total dissolved solids. Screening for salinity first is often a practical starting point.
Do home filters remove radium? Reverse osmosis and ion exchange systems are generally effective. Standard carbon filters are not designed to remove radium.
