The quarterly update will examine this dynamic and rapidly evolving area from multiple perspectives, ensuring its relevance and value to a diverse range of stakeholders including businesses, local authorities, resident groups and NGOs.

This first post in our series is adapted and updated from Claire’s presentation at the Royal Society of Chemistry’s Environmental Toxic Tort Conference in November 2025, which explored the potential for class actions focused on per‑ and polyfluoroalkyl substances (“PFAS”) in the UK. 

Introduction

In contrast to the well‑established practice of large class actions in the USA, the UK has long been regarded as an inhospitable terrain for mass group litigation. That perception is changing as recent jurisprudence has demonstrated both the willingness and capacity of UK courts to manage complex, multi‑party claims. Furthermore, as public and scientific awareness of risks associated with PFAS continues to develop and highlight common exposure patterns and shared harms, prospective claimants are increasingly exploring viable legal avenues for redress.

This post surveys the drivers behind prospective PFAS group actions in the UK, the provisions governing Group Litigation Orders and other forms of group action, and the strong precedent set by the Mariana Dam case for group litigation in the UK.

Increasing appetite for PFAS litigation in the UK

As has already been discussed in previous blog posts exploring potential avenues for redress for PFAS pollution and the challenges and opportunities of chemical regulation, PFAS contamination is no longer a niche concern. It is widely documented across groundwater, surface waters, soils, food chains and consumer products. A 2023 report by the Environment Agency identified over 10,000 potential PFAS high risk sites in England alone and an estimated cost of £31bn-£121bn for their remediation.

Moreover, investigations have highlighted potential hot‑spots including the firefighting foam manufacturer Angus Fire in Bentham (North Yorkshire) and the fluorochemical manufacturing facility AGC Chemicals Europe Ltd at Thornton‑Cleveleys (Lancashire). Potential contamination in Thornton-Cleveleys is currently the subject of an ongoing contaminated land investigation under Part 2A of the Environmental Protection Act 1990. As the first contaminated land investigation focused on PFAS, it has the potential to set an important precedent for how these substances are managed under the contaminated land regime. In the meantime, Wyre Council has advised residents to exercise caution by washing their hands thoroughly after working or playing in gardens or allotments and to wash and peel any produce grown in the soil to remove soil or dust.

Local developments, such as those in Bentham and Thornton-Cleveleys, intersect with regulatory reforms that raise public awareness and concern about the risks associated with PFAS. For example, on 4 July 2025, the use of firefighting foams containing PFOA became unlawful in Great Britain under the UK POPs Regulation (assimilated Regulation (EU) 2019/1021), following the expiry of the derogation in Annex I for legacy PFOA foams.

Similarly, on 18 August 2025, the Health & Safety Executive (HSE) launched a public consultation under UK REACH on a proposed restriction of all PFAS in firefighting foams. That consultation runs until February 2026 and could lead to a future ban on C6 fluorotelomer foams and other PFAS-based formulations. In addition, the EU is preparing to introduce legally enforceable limits for PFAS in drinking water from 12 January 2026 through the recast Drinking Water Directive (Directive (EU) 2020/2184). These (non-exhaustive) examples of regulatory reforms, both implemented and proposed, underscore that the effective management of the recognised risks associated with PFAS remains a pressing policy issue in the public interest.

Moreover, faced with criticism from the charity and independent think tank, Green Alliance, and others about the entrenchment of regulatory divergence between the UK and the EU, on 1 December 2025, the UK Government committed in its revised Environmental Improvement Plan (“EIP”) to reforming UK REACH “to enable protections that address chemical pollution to be applied more quickly, efficiently and in a way that is more aligned with our closest trading partners, especially the EU, by December 2028.” The EIP also promises a PFAS action plan that will set out “measures and initiatives with specific actions and delivery milestones”, that will “identify and address releases of harmful PFAS and protect people and the environment from harm relating to PFAS exposure”.  The contents of that plan will no doubt be informed by the ongoing UK Parliament Environmental Audit Committee’s inquiry on PFAS risks, monitoring and the robustness of UK REACH compared with the EU and US regimes.

While the UK remains in the relatively early stages of developing its regulatory approach to PFAS, those living near potential contamination sources can consider examples from other countries for an indication of the potential risks they might be facing. For example, those concerned about potential PFAS contamination from firefighting foam in the UK can look to the precedent set in Jersey where PFAS pollution linked to the use of firefighting foams at Jersey Airport was discovered in groundwater as far back as the 1990s but recent studies continue to show that groundwater and surface water below the airport fire training ground still contain elevated levels of PFAS. Recent blood tests revealed that the concentration of PFAS in some residents’ blood is of a level that can lead to health problems.

The Changing Landscape of Class Actions in the United Kingdom

Amid an evolving regulatory landscape, growing awareness of risks, and examples of successful group litigation in other jurisdictions which offer valuable insights into potential causes of action, establishing causation, and available remedies, affected communities in the UK are increasingly prepared to pursue legal avenues for redress.

Notwithstanding the challenges of establishing causation for PFAS litigation, which is beyond the scope of this post, group litigation is an obvious port of call for PFAS litigation where cohort definition (e.g., residents near known sources, allotment holders, downstream water users) and exposure pathways are amenable to common‑issue framing.

The principal case‑management instrument is the group litigation order (“GLO”) under CPR Part 19, operating on an opt‑in basis and anchored on identified “GLO issues.” The threshold is modest: the court may make a GLO where a number of claims give rise to common or related issues of fact or law (CPR 19.21–19.26). GLOs are capable of accommodating a wide variety of cases and number of claimants – ranging from a small number such as the Corby Group Litigation – which related to just 18 claims for the mismanagement of toxic waste in the reclamation of a steelworks in Northamptonshire (Corby Group Litigation v Corby District Council [2009] EWHC 1944 (TCC)) to hundreds of thousands.

Although, the Civil Procedures Rules have included provisions for GLOs under Part 19 since 2000, there has been historic reluctance to avail of Part 19 due to concerns around costs, procedural hurdles and the lack of clear precedent for dealing with mass claims in the UK.

However, GLOs are not the only mechanism by which the courts can deal with mass claims. Recent cases have revealed an increased willingness by the courts to manage large-scale cases by deploying their inherent case management powers to separate liability and quantum, stage issues, and impose disciplined disclosure and expert timetables. That pragmatic posture has been critical to enabling very large cohorts to be heard efficiently and eroding the historic perception of the UK as unsuitable for class actions or group claims. Indeed, the recent judgment of Senior Master Jeremy Cook, who refused to grant a GLO brought by former and current students of University College London in David Hammon & Ors v University College London [2024] EWHC 1744 (KB), demonstrates the courts’ increased tendency to prefer ordinary case management powers over GLOs: “Technological and computing developments have revolutionised the way in which lawyers and judges work and manage cases (…) With cooperation and creativity the court’s standard case management powers can be used to replicate almost any feature of a GLO.”

The most consequential development in mass environmental litigation in recent years is the High Court’s liability judgment in Município de Mariana v BHP [2025] EWHC 3001 (TCC)). In November 2025, Mrs Justice O’Farrell found BHP liable to a cohort exceeding 600,000 claimants for the 2015 Fundão tailings dam collapse in Brazil, holding the company strictly liable as a “polluter” under Brazilian environmental law and liable in negligence under the Brazilian Civil Code. The second‑stage (quantum) trial is listed for October 2026.

The Mariana Dam claim was not brought as a GLO but as a CPR Part 7 High Court action with a large number of claimants listed on one claim form. The recent High Court judgment of November 2025 represents a volte face from the 2020 decision of the High Court to initially reject jurisdiction and strike it out as an abuse of process on the basis that it would be “irredeemably unmanageable” and have “a very significantly deleterious impact indeed upon the scarce resources of the English courts” (Municipio de Mariana v BHP Group Plc [2020] EWHC 2930 (TCC) per Turner J at [104]-[105]). That judgment was overturned and the case was reinstated by the Court of Appeal in 2022 which held that the size of a case and number of claimants alone could not support a conclusion of abuse of process.

The Mariana Dam case builds on previous mass claims against English-domiciled parent companies such as Okpabi and others v Royal Dutch Shell Plc and Shell Petroleum Development Company of Nigeria Ltd [2021] UKSC 3 and Vedanta Resources PLC and another (Appellants) v Lungowe and others (Respondents) [2019] UKSC 20 where 40,000 Nigerian residents and 2,500 Zambian villagers brought respective claims against Shell in relation to an oil spill in Nigeria and Vedanta Resources for alleged pollution caused by a copper mine in Zambia. Similarly to the Mariana Dam case, both cases proceeded under the courts’ standard case management powers rather than the structured GLO regime. These cases demonstrate the English courts’ capacity and willingness to effectively manage and decide large-scale claims.

Although Okpabi, Vedanta and the Mariana Dam case relate to international claims involving English-domiciled parent companies, they send a strong signal to potential litigants that the UK courts are well-equipped to deal with complex group action disputes. This principle evidently applies just as much to domestic matters as to cases with an international angle. Furthermore, as PFAS continues to be a live and potentially widespread issue across the UK, these cases indicate how a mass claim concerning PFAS might be handled by the UK courts from a case management perspective.

Conclusion

Although current regulatory gaps, the lack of enforceable standards for PFAS in the UK and the challenges of establishing causation render it premature to predict a flood of PFAS group claims in the UK, examples from Bentham and Thornton-Cleveleys demonstrate that concerned residents are increasingly willing to consider the avenues available to them for legal redress. Large scale group actions in the UK have so far focussed on environmental damage in other jurisdictions, however, increased and widespread concern about PFAS and other pollutants and confidence in the courts’ ability to effectively manage large scale environmental claims may mean we eventually see a second wave of group actions focussed on PFAS. These could take many forms, from mass tort claims brought directly against the alleged polluters to actions against regulators, local authorities and water companies.

Claire Nevin is a planning and environmental barrister at FTB. She is frequently instructed on chemicals and wider pollution and contaminated land matters for a range of clients including local authorities, businesses, resident groups and NGOs.