They’re in your frying pan, your waterproof jacket, your carpet, your mascara – and increasingly, they’re in your drinking water. If you’ve been seeing the term “PFAS” more often and wondering what exactly these “forever chemicals” are and how they end up in our taps, you’re not alone.
This article unpacks what PFAS are, why they are so persistent, and how they contaminate our water and wider environment – drawing on recent science, regulatory reports and real-world examples.
What exactly are PFAS?
PFAS stands for per- and polyfluoroalkyl substances, a large family of synthetic chemicals first developed in the mid-20th century. The Organisation for Economic Co-operation and Development (OECD) estimates there may be more than 10,000 individual PFAS compounds in use or circulation.
What they share is a defining chemical feature: a chain of carbon atoms fully or partially bonded to fluorine atoms – the so‑called carbon–fluorine (C–F) bond. This is one of the strongest bonds in organic chemistry. It gives PFAS their famous (or infamous) properties:
- Heat resistance – they don’t break down easily at high temperatures.
- Water and oil repellence – they create ultra-slick, non-stick and stain-resistant surfaces.
- Chemical stability – they resist degradation by sunlight, microbes and many common chemicals.
Because of this, PFAS have been used in thousands of products, including:
- Non-stick cookware (e.g. Teflon-type coatings)
- Waterproof and stain-resistant textiles (outdoor gear, carpets, upholstery)
- Food packaging (grease-resistant fast-food wrappers, pizza boxes, microwave popcorn bags)
- Firefighting foams, particularly aqueous film-forming foams (AFFF) used at airports and military bases
- Electronics manufacturing, plating, photographic and aerospace industries
- Cosmetics and personal care products (waterproof mascara, long-lasting lipstick, some lotions)
Not all PFAS are equally studied. Regulatory focus has largely centred on a few “legacy” compounds like PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid), but newer “replacement” PFAS are now widely used – and frequently turning up in water, too.
Why are they called “forever chemicals”?
The nickname “forever chemicals” comes from their extraordinary persistence. Unlike many other pollutants that gradually degrade in soil, water or air, PFAS are designed to endure.
In the environment, their C–F bonds are extremely difficult to break. That means that once released, PFAS can persist for decades or longer. Even when they transform chemically, they often turn into other PFAS rather than harmless end products like carbon dioxide or water.
In the human body, some PFAS also have long biological half-lives. For example:
- PFOS and PFOA can stay in the bloodstream for 2–5 years or more, according to biomonitoring data from the US Centers for Disease Control and other studies.
- They can accumulate with ongoing exposure, as the rate of intake can exceed the rate of elimination.
So when a factory discharged PFAS into a river 20 years ago, the contamination is not “historic” in the sense that leaded petrol is historic; the chemicals are frequently still there, moving through groundwater plumes, sediments and food webs.
How PFAS move from products into water and the environment
PFAS start their life in manufacturing plants and consumer products, but they rarely stay put. They move through a series of pathways, eventually ending up in places they were never intended to be – including wells, reservoirs and even remote Arctic ice.
Industrial discharges and manufacturing sites
Historically, one of the most significant sources has been industrial emissions from facilities that manufacture PFAS or use them in processes (e.g. fluoropolymer production, plating, textiles).
PFAS can be released via:
- Wastewater discharges into rivers and streams
- Leaking storage or disposal pits contaminating nearby soil and groundwater
- Air emissions that later deposit back onto land and water through rain and dust
Once PFAS enter a water body, they mix, disperse and can infiltrate groundwater aquifers. Many documented contamination cases worldwide – from the US and Europe to Australia and Asia – trace back to industrial sources.
Firefighting foams: a long-lived legacy
Another major source is AFFF firefighting foam used for high-intensity fuel fires. These foams rely on PFAS to create a thin film that cuts off oxygen and spreads quickly over burning fuel.
For decades, training exercises and emergency responses at airports, refineries, military bases and chemical plants involved large volumes of foam discharged directly onto soil or into unlined pits. There, PFAS compounds infiltrated the ground and formed persistent groundwater plumes that can migrate kilometres from their original source.
Even when foam use has stopped, the contamination they left behind continues to move through subsurface water systems and can reach municipal wells and private boreholes long after the final training exercise took place.
Consumer products and indoor environments
PFAS-treated consumer products also act as diffuse, everyday sources. Here, the release mechanisms are different but no less important.
- Textiles and carpets can shed PFAS-laden dust and fibres that accumulate indoors, then move outwards via ventilation, cleaning water or waste streams.
- Food packaging can transfer PFAS into food, and used packaging often ends up in landfills or incinerators, where PFAS may leach into leachate or be emitted to air.
- Cosmetics and personal care products washed off in the shower carry PFAS into household wastewater and ultimately into sewage treatment plants.
These “everywhere” sources are harder to identify individually, but collectively they contribute to the background PFAS load in sewage sludge, urban runoff and indoor dust, which can then re-enter the outdoor environment.
Wastewater treatment plants and sludge
Here’s a crucial point: most conventional wastewater treatment plants are not designed to remove PFAS. Biological treatment steps that work well for nutrients and many organic pollutants barely touch PFAS.
That means PFAS entering sewage plants from households, hospitals and industry often pass through largely unchanged and are discharged to receiving waters.
At the same time, PFAS can concentrate in sewage sludge (biosolids). When this sludge is applied to agricultural land as fertiliser – a common practice in many countries – PFAS can:
- Leach through soils into underlying groundwater
- Be taken up to some extent by crops and pasture plants
- Wash off into surface waters during heavy rainfall events
Several European case studies have documented elevated PFAS levels in soil, groundwater and agricultural produce near fields treated with contaminated sludge, underscoring this pathway.
Airborne transport and global spread
PFAS are often framed as a water problem, but airborne transport plays a significant role in how widely they spread.
Some PFAS are volatile or semi-volatile, or are emitted as aerosols during industrial processes and foam use. These substances can travel long distances before depositing back onto land or water via rain or dry deposition. Over time this contributes to low but measurable PFAS levels even in remote, seemingly pristine regions.
Scientists have detected PFAS in:
- Arctic and Antarctic snow
- High-altitude lakes and mountain catchments
- Sea spray aerosols, which can re-emit PFAS back into the atmosphere
This paints a clear picture: once released, PFAS don’t stay local. They join a global cycle.
How PFAS end up in drinking water
The step from “environmental contamination” to “what comes out of the tap” depends on how a community sources and treats its water.
PFAS can contaminate:
- Groundwater – particularly near industrial sites, landfills, airfields or areas with historical foam use. Private wells and municipal boreholes can be affected.
- Surface water – rivers, lakes and reservoirs that receive industrial wastewater, treated sewage effluent or runoff from contaminated land.
- Bank filtration and artificial recharge zones – where surface water is deliberately infiltrated to recharge aquifers, PFAS can be carried into previously clean groundwater.
Standard drinking water treatment (coagulation, sedimentation, sand filtration, chlorination) removes particulates and many microbes, but is not very effective for most PFAS. Unless specific advanced treatments are added – such as granular activated carbon, ion exchange resins or reverse osmosis membranes – PFAS can slip through to the consumer.
Health and ecological impacts: what does the science say?
PFAS toxicology is an active research field, and not every compound has been studied in depth. However, for several well-known PFAS, such as PFOA and PFOS, there is a growing body of evidence linking exposure to a range of health effects.
Major scientific reviews, including those by the European Food Safety Authority (EFSA), the US National Academies of Sciences and other agencies, have associated certain PFAS exposure levels with:
- Changes in cholesterol levels
- Altered liver enzymes
- Reduced immune response, including lower vaccine antibody levels in children
- Reduced birth weight and potential developmental effects
- Increased risk of some cancers, such as kidney and testicular cancer (for PFOA in particular)
- Thyroid hormone disruption
It’s important to note that most people are exposed to mixtures of multiple PFAS at low levels, typically via food, water and dust. That makes it complex to untangle cause and effect, but the overall direction of the research has pushed regulators towards increasingly strict guidelines, often in the single-digit nanogram-per-litre (ng/L) range for drinking water.
In ecosystems, PFAS can:
- Bioaccumulate in fish, birds and marine mammals
- Interfere with reproduction, development and immune function in wildlife
- Transfer up food chains, leading to higher concentrations in top predators
That’s why PFAS contamination is not just a drinking water issue; it’s also a biodiversity and food security concern.
Regulation is tightening – but the chemicals are already out there
In recent years, regulators in Europe, North America and elsewhere have introduced or proposed:
- Phase-outs and bans on specific PFAS like PFOS and PFOA in many applications
- Drinking water standards for selected PFAS, or sums of PFAS
- Restrictions on PFAS in food contact materials and some consumer products
- Moves towards a “grouping” approach, regulating PFAS as a class instead of compound by compound
However, production of other PFAS continues, and legacy contamination is widespread. From a water perspective, that means utilities and individual households are increasingly grappling with the question: how do we remove PFAS that are already present?
Removing PFAS from drinking water: what actually works?
For all their persistence, some PFAS can be effectively reduced in drinking water with the right technologies. Three main approaches are commonly used:
- Granular activated carbon (GAC) – PFAS molecules adsorb onto the surface of activated carbon. This is widely used at municipal scale and in some household filters. It tends to work better for longer-chain PFAS (like PFOS, PFOA) than for some shorter-chain replacements.
- Anion exchange resins – Specialised resins attract and hold negatively charged PFAS ions. They can achieve high removal efficiencies and are increasingly deployed in treatment plants.
- Reverse osmosis (RO) – A membrane process that rejects a wide range of dissolved contaminants, including many PFAS. Common in point-of-use systems under kitchen sinks and in some desalination and advanced treatment plants.
Each technology has trade-offs in terms of cost, energy use, waste generation (spent carbon or concentrated brine) and performance across different PFAS types. No single solution is universally perfect, but these tools provide practical ways to reduce exposure while upstream pollution sources are addressed.
What can individuals and communities do?
PFAS contamination is, fundamentally, a systemic problem that requires regulatory action and industrial change. That said, there are meaningful steps that individuals and communities can take:
- Stay informed – Check whether your local water provider publishes PFAS monitoring data. In some regions, public databases or mapping tools are available.
- Consider certified filtration – If PFAS are a concern in your area, look for home filtration systems independently certified to reduce PFAS (for example under relevant NSF/ANSI standards). Not all filters are equal.
- Reduce PFAS-containing products – Opt for PFAS-free cookware, textiles, cosmetics and food packaging where possible. Manufacturers are increasingly labelling PFAS-free alternatives.
- Engage with policy – Public input can influence regulations around industrial discharges, firefighting foams, PFAS use in consumer goods and investment in advanced water treatment.
- Support monitoring and research – Community science projects and local studies can help identify contamination hotspots and drive remediation efforts.
On their own, these actions won’t erase decades of PFAS use, but they can reduce personal exposure, send market signals to producers and support broader shifts in policy and practice.
From invisible molecules to visible change
PFAS are a textbook example of how a powerful chemical innovation, adopted widely before its long-term impacts were understood, can shape our environment for generations. They are invisible in water, odourless and tasteless at the levels typically found – yet they leave a clear fingerprint in blood tests, wildlife tissues and water quality data across the globe.
Understanding what PFAS are, how they move through industrial systems and ecosystems, and how they end up in our drinking water is the first step towards managing them more intelligently. The science is advancing quickly; regulation is catching up; and filtration technologies are improving. The real challenge now is aligning all three with a simple goal: water that is truly clean, not just clear.