What are Forever Chemicals in Water?

By Ankit SinghReviewed by Laura ThomsonDec 1 2025

Forever chemicals in water are rushing up the political and scientific agenda, as evidence of their persistence and health impacts grows. In the UK, industry body Water UK has called for a ban on these chemicals to prevent long-term buildup in the environment, while stating it remains confident that drinking water is currently safe. This combination of caution and reassurance captures the central tension around forever chemicals in water today. The challenge now is to phase out avoidable uses and manage legacy pollution without compromising public trust in water supplies.¹

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Forever Chemicals: A Definition

Forever chemicals in water generally refer to per- and polyfluoroalkyl substances, commonly known as PFAS.

PFAS is a broad class of over 10,000 synthetic compounds characterized by strong carbon-fluorine bonds. These bonds give PFAS exceptional resistance to heat, acids, and biological degradation, so they can persist in the environment for decades or longer once released.?^2,3

PFAS include well-known chemicals such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), as well as newer short-chain and polymeric variants that manufacturers introduced as substitutes.

Many PFAS have both water-repelling and oil-repelling properties, which explains their widespread use. However, these properties also affect how PFAS move through soils, water, and living tissues.^2,3

Industrial and Everyday Uses

PFAS entered modern economies through industrial processes that require stable surfactants, high-performance coatings, and reliable foaming agents. They are extensively used in metal plating, electronics manufacturing, and the production of specialized lubricants, where equipment safety and product performance depend on materials that do not break down under stress.?^2,3,4

In consumer markets, PFAS occur in stain-resistant textiles, nonstick cookware, grease-resistant food packaging, certain cosmetics, and some medical devices. Aqueous film-forming foams used to fight fuel fires at airports and industrial sites represent another major historical use, and these foams have been a significant source of groundwater contamination.?^2,3,4

How do PFAS Enter Water Networks?

PFAS reach drinking water networks through several distinct pathways that interact over long time scales. Industrial discharges, landfill leachate, sewage effluent, and firefighting foam residues can all dump PFAS into surface waters and aquifers that serve as raw water sources.?^2,5

Once in the environment, many PFAS dissolve in water or bind to particles. They can travel with river currents, infiltrate groundwater, and accumulate in lakes and reservoirs that are used for drinking water supplies.

Wastewater treatment plants often pass PFAS through rather than degrade them, and the land application of biosolids containing PFAS can create diffuse sources that slowly reintroduce contamination into the water cycle.?^2,4,5

Health Risks and Scientific Uncertainty

PFAS toxicity depends on the specific compound, exposure level, and life stage of the individual, but several well-researched substances have been associated with concerning health effects. Epidemiological and toxicological studies link high levels of PFAS exposure to negative impacts on the liver, immune system, lipid metabolism, thyroid function, reproduction, and development.^3,6,7

Recent large-scale analyses also report associations between PFAS in drinking water and increased incidence of several cancers, including those of the digestive, endocrine, respiratory, and urinary systems, although these findings still carry uncertainties typical of ecological studies.

Long biological half-lives for some PFAS mean that even low drinking water concentrations can contribute to body burdens that last for years, which motivates very low health advisory values in some jurisdictions.?^6,7,8

How Safe Is Drinking Water Today?

Public concern about forever chemicals often centers on drinking water, as it represents a daily and involuntary exposure route. Organizations like Water UK stress that current monitoring data and precautionary guidance values indicate that drinking water in the UK is safe, while still advocating for upstream bans to prevent future accumulation.?^1,2,9

Regulators and public health agencies are increasingly framing safety in terms of both absolute concentrations and long-term exposure. This has led to tighter advisory levels and more frequent testing.

In the UK, the Drinking Water Inspectorate recommends a guideline limit of 0.1 micrograms per liter for individual PFAS compounds, along with a tiered response framework. This framework directs water companies to investigate and remediate if levels exceed this guideline.^8,9

Treatment Tools for Water Companies

Water companies can reduce the levels of PFAS at treatment facilities by using targeted technologies that remove these persistent molecules from raw water. Effective methods include granular activated carbon, ion-exchange resins, and specific high-pressure membrane processes, such as nanofiltration and reverse osmosis, all of which demonstrate significant removal efficiencies for many types of PFAS, particularly the longer-chain species.^5,10

These technologies create new responsibilities because PFAS accumulate in spent media and brines, which then require secure disposal or high-temperature destruction.

Research into microbial biotransformation and advanced oxidation aims to complement existing methods by breaking down PFAS rather than merely transferring them from water to another waste stream. However, achieving full mineralization at scale remains a significant technical challenge.^3,5,11

Practical Limits on Treatment

Technical potential does not always translate into rapid, universal deployment across water networks.

Retrofitting treatment plants with advanced PFAS removal technologies entails high capital costs, increased energy demands, and ongoing expenses for media replacement and waste management. This can be very challenging for smaller utilities or rural systems.^4,5,10

Water companies must balance PFAS control with other regulatory obligations, such as reducing nutrient discharges, managing combined sewer overflows, and adapting to climate-driven extremes that impact supply reliability.

Due to these competing priorities, it is more practical to focus targeted investments on the most affected areas, utilizing risk mapping and monitoring, rather than pursuing uniform upgrades across all systems.^1,4,12

The Scale of PFAS Pollution in the Environment

PFAS contamination is found on every inhabited continent, affecting environments from remote polar regions to densely populated cities. Measurements have detected PFAS in surface water, groundwater, rainwater, soils, sediments, and wildlife. This confirms that these chemicals spread globally through air and water, with local sources contributing to their regional and even worldwide distribution.^2,13

Studies of both raw and treated drinking water reveal that many water systems contain detectable levels of PFAS. These levels can vary widely, often falling below current health-based guidelines.

The European Environment Agency has reported instances of PFAS exceeding proposed thresholds in a significant portion of monitored water bodies, highlighting the need for coordinated management at the basin scale rather than isolated efforts at individual treatment plants.^4,5,10,13

What the Future May Look Like

The future of forever chemicals in water will depend on how quickly societies reduce PFAS emissions while improving treatment where contamination already exists. A possible path forward involves phased bans on non-essential uses of PFAS and stricter regulations on products containing these chemicals. Moreover, expanding monitoring of both raw and treated water, along with investing in advanced treatment technologies for high-risk water supplies, is essential for ensuring safety.^3,4,9

Under this scenario, overall environmental PFAS loads may plateau and then gradually decline; however, legacy contamination in soils, aquifers, and sediments will continue to result in low-level exposure for decades.

Continued engagement by industry bodies such as Water UK, combined with transparent communication of monitoring data and health evidence, will build public trust. It will also guide practical decisions about where interventions can have the most significant impact.^1,2,4

References and Further Reading

1. Stallard, E. et al. (2025). Firms ordered to reduce forever chemicals in drinking water sources for 6 million people. BBC. https://www.bbc.com/news/articles/c9q1nzyzyjeo
2. Evich, M. G. et al. (2022). Per- and polyfluoroalkyl substances in the environment. Science. DOI:10.1126/science.abg9065. https://www.science.org/doi/10.1126/science.abg9065
3. Wee, S. Y., & Aris, A. Z. (2023). Revisiting the “forever chemicals”, PFOA and PFOS exposure in drinking water. Npj Clean Water, 6(1), 57. DOI:10.1038/s41545-023-00274-6. https://www.nature.com/articles/s41545-023-00274-6
4. PFAS risk and management in the water industry - Policy Position Statement. (2024). Chartered Institution of Water and Environmental Management (CIWEM). https://www.ciwem.org/policy-reports/pfas-pps
5. Sadia, M. et al. (2023). Occurrence, Fate, and Related Health Risks of PFAS in Raw and Produced Drinking Water. Environmental Science & Technology. DOI:10.1021/acs.est.2c06015. https://pubs.acs.org/doi/10.1021/acs.est.2c06015
6. Li, S. et al. (2025). Associations between per-and polyfluoroalkyl substances (PFAS) and county-level cancer incidence between 2016 and 2021 and incident cancer burden attributable to PFAS in drinking water in the United States. Journal of Exposure Science & Environmental Epidemiology, 35(3), 425-436. DOI:10.1038/s41370-024-00742-2. https://www.nature.com/articles/s41370-024-00742-2
7. Peritore, A. F. et al. (2023). Current Review of Increasing Animal Health Threat of Per- and Polyfluoroalkyl Substances (PFAS): Harms, Limitations, and Alternatives to Manage Their Toxicity. International Journal of Molecular Sciences, 24(14), 11707. DOI:10.3390/ijms241411707. https://www.mdpi.com/1422-0067/24/14/11707
8. Historical PFOA and PFOS Health Effects Science Documents. US EPA. https://www.epa.gov/sdwa/historical-pfoa-and-pfos-health-effects-science-documents
9. PFAS and Forever Chemicals. UK Drinking Water Inspectorate. https://www.dwi.gov.uk/pfas-and-forever-chemicals/
10. Polychronidou, V., & Nag, R. (2025). Human health risk assessment of Per- and polyfluoroalkyl substances (PFAS). Science of The Total Environment, 1000, 180428. DOI:10.1016/j.scitotenv.2025.180428. https://www.sciencedirect.com/science/article/pii/S0048969725020686
11. Skinner, J. P. et al. (2025). Biotransforming the “Forever Chemicals”: Trends and Insights from Microbiological Studies on PFAS. Environmental Science & Technology. DOI:10.1021/acs.est.4c04557. https://pubs.acs.org/doi/10.1021/acs.est.4c04557
12. A Reset for Water: Water UK’s response to the Independent Water Commission’s Call for Evidence. (2025). Water UK. https://www.water.org.uk/news-views-publications/publications/independent-water-commission
13. ‘Forever chemicals’ found above threshold levels in many water bodies in Europe. (2024). European Environment Agency. https://www.eea.europa.eu/en/newsroom/news/forever-chemicals-in-water-bodies

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