PFAS – the “forever chemicals” threatening our water

What Are PFAS?

Poly- and perfluoroalkyl substances (PFAS) are a large family of over 7,000 synthetic chemicals that have been in use since the 1940s. Known for their durability, PFAS contain strong carbon-fluorine bonds, making them resistant to heat, water, and chemical degradation—hence the nickname “forever chemicals.”1

Recent UK monitoring data has revealed widespread PFAS contamination in the water environment. These substances can accumulate in the food chain and pose risks to both ecosystems and human health, including potential links to cancer.

Why Are PFAS Used?

PFAS are valued for their oil- and water-repellent properties, as well as their resistance to heat and wear. They are used across a wide range of industries, including:

  • Firefighting foams
  • Metal finishing and plating
  • Hydraulic fluids
  • Fluoropolymer production
  • Paper and packaging
  • Semiconductor manufacturing
  • Textiles and leather (e.g., carpets and furniture)

In the UK, key sources include airports, fire training sites, landfills, hazardous waste incinerators, and facilities in the textile, paper, and chemical sectors.

While PFAS-free alternatives exist, transitioning away from PFAS can be costly and technically challenging—especially in sectors like electronics and healthcare. Substitutes such as polyethylene, silicon, wax, and acrylates may not meet legal standards for thermal resistance and durability.

Regulatory Updates for the Water Environment

Regulations are evolving as new toxicity data emerges. Key updates include:

  • UK Drinking Water Inspectorate (DWI): Currently monitors 47 PFAS compounds. From January 2025, 6:2 fluorotelomer sulfonamide alkylbetaine (FTAB), also known as Capstone B, will be added due to its environmental persistence and health concerns.
  • Monitoring Requirements: A new three-tier risk-based system will apply to PFAS detected in untreated raw and final water. Water companies must report any PFAS found at concentrations below 0.01 µg/L, even if not on the official list.
  • Expanded Guidance: Existing rules for PFOS and PFOA will be extended to all PFAS listed in Annex C of the Water Industry (Suppliers’ Information) Direction 2019.

PFOS and PFOA are already restricted under UK REACH and classified as persistent organic pollutants under the Stockholm Convention.

Recent Regulatory Developments

  • DWI Guidance: 0.01 µg/L threshold for PFAS (Tier 1), expanding to 48 compounds in 2025.
  • EU Water Framework Directive: Proposed update to include 24 PFAS compounds with a combined limit of 0.1 µg/L.
  • CL:AIRE Interim Screening Levels: Set for four key PFAS compounds—PFOA, PFNA, PFHxS, and PFOS.

The Way Forward

The UK’s approach to managing PFAS is built on four pillars:

  1. Evidence: Enhanced monitoring, environmental targets, and analytical development.
  2. Source Control: Preventing new PFAS inputs through regulatory restrictions.
  3. Regulatory Framework: Engaging stakeholders, prioritising sectors, and updating permitting regulations.
  4. Legacy Management: Addressing contamination at legacy sites through screening and remediation projects.

Successfully phasing out PFAS will require collaboration across industry, scientific research, policy-making, and regulation.

  1. EA Chief Scientist’s Group Report, Poly- and perfluoroalkyl substances (PFAS): sources, pathways and environmental data (2021). ↩︎