How Climate Change Influences the Spread of PFAS in Water Sources
As the climate crisis intensifies, its ripple effects extend into domains we might not immediately consider—like the spread of persistent toxic chemicals in our environment. Among the most concerning of these chemicals are per- and polyfluoroalkyl substances (PFAS), commonly dubbed « forever chemicals » due to their resistance to degradation. While PFAS contamination has already affected drinking water supplies worldwide, climate change may be accelerating the pathways through which these substances migrate into our water systems.
But how exactly does rising global temperature, intensified rainfall, and shifting hydrological patterns influence PFAS mobility? Let’s delve into how the changing climate is unwittingly reshaping the chemistry of our water.
PFAS Meet Climate Change: A Hazardous Combination
The term “forever chemicals” isn’t hyperbole. PFAS are notoriously stable due to strong carbon-fluorine bonds, making them resistant to heat, water, and oil. This same resilience means they persist in the environment for decades—accumulating in soil, leaching into groundwater, and moving through rivers and streams. Now, with the added variable of climate change, their environmental footprint is growing in ways scientists are working hard to understand.
Here are some of the climate-driven mechanisms that can exacerbate PFAS spread:
- Increased flooding and stormwater runoff
- Rising temperatures impacting PFAS volatility
- Sea level rise and saltwater intrusion into freshwater sources
- Changes in soil chemistry and hydrology due to droughts and heavy rains
Each of these factors creates new scenarios for exposure, movement, and bioaccumulation of PFAS in aquatic ecosystems. Let’s unpack them one by one.
Flooding: A New Vector for PFAS Mobilisation
More frequent and intense flooding is one of the most visible consequences of climate change. As atmospheric temperatures rise, they allow the air to hold more moisture, leading to heavier rainfall. When rivers overflow, or storm drains spill into surrounding neighborhoods and fields, they pick up whatever contaminants are in their path—including PFAS residues from firefighting foam sites, landfills, industrial facilities, and even airports.
Floodwaters can swiftly spread these substances across wide areas, flushing them into lakes, reservoirs, and municipal water supplies. A study led by Harvard University in 2022 found that communities downstream from flooding events near military bases in the U.S. experienced spikes in PFAS concentrations in surface water—sometimes exceeding EPA advisory limits by tenfold.
In the UK, where PFAS have been detected in areas such as the River Wyre and near Heathrow airport, increased precipitation poses a significant risk of mobilising legacy contamination. This translates to growing challenges for water authorities already working hard to monitor and mitigate PFAS.
Heat and Volatility: PFAS Are on the Move
While PFAS are generally considered non-volatile, research shows that some shorter-chain PFAS precursors can enter the atmosphere via evaporation, especially under high-temperature conditions. From there, they can travel significant distances before redepositing through rainfall—a process known as atmospheric deposition.
As global temperatures continue to rise, scientists are investigating how heat-driven volatilisation might contribute to airborne PFAS cycling. In urban and industrial centres, hot summers could worsen atmospheric PFAS burdens, increasing the contamination load in rainwater that eventually percolates into freshwater reservoirs.
This secondary transport mechanism means that PFAS aren’t just a local issue—they’re becoming a planetary one, carried by wind and rain to regions previously unaffected.
Saltwater Intrusion and Coastal Vulnerability
Sea level rise, another direct outcome of climate change, introduces yet another pathway for PFAS migration. As seawater moves inland, it pushes saltwater into coastal aquifers. In turn, these saline waters can disturb chemical equilibria and remobilise sorbed PFAS compounds in sediment or soil matrices.
Areas such as East Anglia or low-lying parts of the Thames Estuary are particularly at risk. Because many PFAS compounds carry anionic charges, they interact with metals and organic matter in complex ways. Saltwater intrusion changes the ion exchange dynamics in groundwater, potentially releasing PFAS that had previously been immobilised in aquifer soils.
Moreover, coastal wastewater treatment plants may face additional burdens. They already struggle to fully remove PFAS, and rising tides could force retrofits or redesigns to prevent backflow contamination from surrounding seawater.
Extreme Weather Alters PFAS Behaviour in Soil
Soil serves as both a reservoir and a conduit for PFAS. During dry periods, PFAS can accumulate in the upper soil layers. But when rainfall returns—especially in the form of sudden, heavy downpours—these chemicals are flushed downward with the infiltrating water. This rapid leaching increases the risk of contamination reaching underlying aquifers that serve as drinking water sources.
This boom-and-bust cycle of droughts followed by deluges is already being observed across the UK, especially in agricultural areas reliant on aquifer-fed irrigation. If PFAS are present in biosolids used as fertilisers, for example, drought can concentrate them in soils, only for a downpour to wash them into nearby waterways.
Researchers from the University of Birmingham are currently studying such dynamics through field trials aimed at measuring PFAS movement under simulated climate conditions. Early findings suggest that soil moisture level is a key factor in determining whether PFAS compounds bind to particles or move freely through the soil profile.
Melting Ice and the Release of Legacy Pollution
While not an immediate issue for the UK, the melting of glaciers and permafrost in Arctic regions poses a profound global risk. These icy environments have served as sinks for PFAS and other persistent organic pollutants (POPs) over decades. As the climate warms, these frozen reservoirs are beginning to release their toxic archives into global water systems.
In 2020, scientists in Sweden and Norway found elevated PFAS levels in glacial meltwater, suggesting that these long-buried chemicals are now being reintroduced into aquatic ecosystems. Ocean currents and atmospheric transport can then distribute these compounds far from their original source, eventually making their way to inhabited regions through rainfall and groundwater flow.
This phenomenon serves as a stark reminder: the environmental legacy of PFAS is not just tied to current use, but also to historical emissions that are being reactivated by our changing climate.
What Does This Mean for Water Safety and Policy?
The intersection between climate change and PFAS contamination presents unique challenges for public health, environmental management, and policy frameworks. Here’s where action is urgently needed:
- Enhanced monitoring: Especially after flooding or extreme weather events, real-time water quality testing for PFAS is essential.
- Improved filtration infrastructure: Water treatment facilities must adopt advanced technologies such as activated carbon or reverse osmosis to address increasing PFAS loads.
- Climate-conscious risk assessments: Regulatory bodies should include climate projections in PFAS mitigation planning—especially in vulnerable regions near flood plains or coasts.
- Research incentives: More studies are needed to understand how PFAS precursors behave under various climatic conditions and how best to intercept them before they spread.
On the regulatory front, there is growing momentum in both the EU and the UK to address PFAS systemically. But as climate change begins to shift the parameters of environmental contamination, regulations must evolve to reflect these new realities—as static policies may not capture the dynamic nature of PFAS behaviour in a rapidly warming world.
A Wake-Up Call in Disguise
In some ways, climate change acts as an accelerant to the PFAS crisis—bringing to the surface what was previously buried, amplifying pathways of exposure, and complicating control efforts. But it also forces us to recognise the interconnectedness of global systems and the need for integrated solutions.
By acknowledging these links, we can better prepare for a future in which chemical safety and climate resilience are considered two sides of the same coin. And perhaps, just perhaps, we can turn that realisation into tangible action—before the next flood brings more than just water to our front door.