PFAS in Drinking Water: A Policy Watch for 2024 and Beyond
The regulatory turning point
April 2024 brought the most consequential regulatory action on per- and polyfluoroalkyl substances (PFAS) in drinking water since the compounds were first regulated. The US Environmental Protection Agency finalised Maximum Contaminant Levels (MCLs) of 4 parts per trillion (ppt) for PFOA and PFOS, and a Hazard Index approach for four other compounds (PFNA, PFHxS, HFPO-DA and PFBS). Water systems serving 25 or more people will need to comply by 2027.
WHO guidance and the EU trajectory
The WHO 2022 interim guideline values set 0.10 µg/L for PFOA and 0.10 µg/L for PFOS individually in drinking water. The EU Drinking Water Directive (DWD, 2020/2184) has set a sum-of-PFAS limit of 0.10 µg/L for the 20 PFAS of greatest health concern, effective from January 2026. Both thresholds are well below the detection capabilities of most routine monitoring programmes, creating immediate demand for updated analytical methods, reference standards and laboratory accreditation.
Treatment implications
Granular activated carbon (GAC) remains the most widely deployed removal technology, achieving 90%+ removal of long-chain PFAS when contact time exceeds 10 minutes and the GAC is fresh. Short-chain PFAS (C4–C6) are significantly harder to remove and require either high-pressure membrane systems (nanofiltration or reverse osmosis) or ion-exchange resins. The US EPA's Technology Design Guidance for PFAS Treatment Systems (2023) estimates capital costs of US $200–600/m³/d for GAC systems and US $800–2,000/m³/d for ion exchange, depending on influent concentrations and system scale.
What utilities should do now
- Audit your monitoring programme: EPA Method 533 and 537.1 cover the regulated compounds; confirm your laboratory has current accreditation for these methods at the required reporting limits.
- Evaluate GAC capacity and contact time against incoming PFAS concentrations — many GAC systems designed for taste-and-odour removal will need expanded contactors.
- Begin source control conversations: engagement with industrial dischargers upstream is faster and cheaper than end-of-pipe treatment at scale.