Researchers warn that drought‑driven lower river flows can raise concentrations of PFAS — persistent "forever chemicals" — in drinking water by reducing dilution. Regulators remain focused on legacy PFAS such as C8 because toxicity data are stronger, even as newer replacements like GenX appear in rivers. Both drought and heavy rain can elevate PFAS depending on local sources; residents should ask their water utility about test results and consider NSF‑certified filters for removal.
Drought Shrinks Rivers — May Concentrate PFAS in Tap Water, Virginia Researcher Warns
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Drought is most often discussed as a threat to water supply or as a factor that worsens wildfires. But a Virginia researcher warns it can also change what ends up in drinking water — notably per‑ and polyfluoroalkyl substances (PFAS), the persistent industrial chemicals often called "forever chemicals."
What the Research Shows
Kirin Furst, an associate professor of civil and environmental engineering at Virginia Tech and co‑director of the Occoquan Watershed Monitoring Laboratory, told public radio station WVTF that reduced river flows during droughts can raise PFAS concentrations in some waterways. "Under lower flow conditions, which you see in a drought, you can see an increase in PFAS concentrations," she said, noting that outcomes depend on local contamination sources.
Legacy Versus Newer PFAS
Regulators have focused particular attention on legacy PFAS — for example, C8, historically used in products such as Teflon — because there is more toxicity data for these compounds and evidence they can be especially hazardous. At the same time, manufacturers have shifted to newer PFAS variants. One replacement chemical, GenX, has been detected in the Roanoke River, illustrating the evolving mix of contaminants utilities must monitor.
"These are the ones that regulators are focusing on the most, those legacy PFAS. In part because we think they're particularly toxic. In part maybe just because we have more data about their toxicities," Furst said.
Why Weather Matters
Both low flows and heavy rainfall can elevate PFAS levels, depending on local pollution sources. Drought concentrates contaminants by reducing dilution, while heavy rain can wash industrial or contaminated sites into streams and rivers. That variability complicates water‑quality monitoring and long‑term risk assessments.
Health Risks And Practical Steps
Health risks from many PFAS are associated with long‑term, repeated exposure. Studies have linked certain PFAS to reproductive harms, developmental delays, and some cancers. For residents concerned about exposure, experts recommend contacting your local water utility to ask what PFAS have been detected and how frequently testing is performed.
Home water filtration can reduce PFAS in drinking water, but not all filters are effective. The U.S. Environmental Protection Agency advises consumers to look for National Sanitation Foundation (NSF) certifications that specifically cover PFAS reduction when selecting a filter.
Scientists are continuing to study how PFAS move through the environment and how best to remove them. As Furst put it: "So it seems like just a global phenomenon at this point. Like we've just injected so much PFAS … that it's gonna be there awhile."
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