Treated tap water in England and Wales is generally within the current DWI (Drinking Water Inspectorate) safety limits for PFAS. However, trace amounts have been detected in some supplies, and 35–37% of UK rivers and groundwater sources show elevated PFAS levels — meaning the contamination challenge is upstream of treatment, not yet at the tap in most cases. The government published its first-ever PFAS action plan in February 2026, and DWI published updated guidance in March 2025 requiring all water companies to monitor a wider range of compounds and tighten their risk assessments. The situation is being actively managed — but it is a genuine, long-term challenge for the sector.
What Are PFAS?
PFAS stands for per- and polyfluoroalkyl substances — a family of more than 4,700 synthetic chemical compounds first developed in the 1940s. They were prized by manufacturers for their exceptional resistance to heat, oil and water, leading to widespread use in non-stick cookware (Teflon), waterproof clothing, food packaging, firefighting foam (AFFF), stain-resistant fabrics and many industrial processes.
The property that made them so commercially useful is also what makes them a public health concern: the carbon-fluorine bond at the heart of their structure is one of the strongest in organic chemistry. PFAS compounds do not break down in the environment. They accumulate in soil, enter waterways, concentrate in food chains and — because they are water-soluble — dissolve into groundwater that eventually supplies drinking water treatment works.
The "forever chemicals" nickname is accurate in a strict sense: once PFAS are in the environment, conventional natural processes do not eliminate them. They can only be removed through engineered treatment systems.
How Did PFAS Get Into UK Drinking Water?
PFAS enter water sources through several routes:
- Firefighting foam (AFFF): Military bases, airports, oil terminals and fire training facilities have historically used aqueous film-forming foam containing high concentrations of PFAS. Spills, leaks and training exercises have contaminated soil and groundwater around many of these sites for decades. Contaminated groundwater then migrates into rivers and drinking water catchments.
- Industrial discharges: Manufacturing sites producing or using PFAS-containing products have discharged PFAS into waterways directly or via wastewater treatment works (which are not designed to remove them).
- Agricultural runoff: PFAS-containing pesticide formulations and sewage sludge (biosolids) applied to farmland have spread PFAS contamination into agricultural catchments.
- Landfill leachate: Older landfill sites containing consumer products with PFAS coatings leach compounds into groundwater over time.
The key point is that PFAS contamination in drinking water is almost entirely a source water problem, not a treatment failure. Water companies inherit the contamination from the environment around their catchments. Addressing it properly requires both upstream prevention and downstream treatment.
What Are the UK Limits — and What Has Been Found?
In March 2025, the Drinking Water Inspectorate published updated PFAS guidance for water companies in England and Wales. The guidance requires companies to monitor a wider range of PFAS compounds and sets a guideline value of 0.1 micrograms per litre (µg/L) for the sum of 48 named PFAS compounds. That is equivalent to 0.1 parts per billion — an extremely low concentration.
The DWI guidance operates through a tiered risk framework:
| Tier | Total PFAS Concentration | Required Response |
|---|---|---|
| Tier 1 | Less than 0.01 µg/L | Standard monitoring programme — no immediate action required |
| Tier 2 | 0.01 to 0.1 µg/L | Enhanced monitoring; risk assessment; consider additional treatment |
| Tier 3 | Greater than 0.1 µg/L | Emergency action required; implement treatment to reduce concentrations below guideline; notify DWI |
In terms of what has actually been found: a 2025 study of London tap water by Imperial College found PFAS present in samples from homes and drinking water fountains across the capital — but always at levels well below DWI limits. However, separate analysis has shown that 35% and 37% of water courses tested in England and Wales contain medium or high risk levels of PFOS and PFOA respectively (two of the most widely studied PFAS compounds). That is the upstream challenge: rivers and groundwater used as source water for treatment works are widely PFAS-contaminated, even if treatment is currently holding finished water within limits.
The DWI guideline value of 0.1 µg/L for PFAS is already set at an extremely cautious level — far below concentrations at which health effects have been demonstrated in studies. This is deliberate: regulators apply large safety margins when dealing with compounds whose long-term cumulative effects are still being studied. The presence of PFAS within guideline limits should not be confused with "safe at any concentration" — it means that concentrations are within the limits regulators consider acceptable given current evidence.
What Are the Health Concerns?
PFAS research is an active and evolving field. The health effects most consistently associated with high PFAS exposure in occupational and epidemiological studies include: increased risk of certain cancers (particularly kidney and testicular cancer), liver and thyroid function changes, immune system effects (reduced vaccine response in children), reproductive and developmental effects, and raised cholesterol levels.
It is important to note that most of this evidence comes from populations with significantly higher PFAS exposure than typical UK tap water consumers — workers at PFAS manufacturing facilities, communities living adjacent to heavily contaminated sites, or populations in countries with weaker regulation. The health risk from UK tap water at current DWI-compliant concentrations is assessed by regulators as low. But "low" is not zero, and the precautionary tightening of limits reflects that the science on long-term, low-level exposure is not fully settled.
What Is the UK Government Doing?
On 3 February 2026, the UK Government published England's first-ever national plan to tackle PFAS — a significant policy step that reflects growing recognition of the scale of the problem. The plan announced a forthcoming consultation on introducing a statutory (legally binding) limit for PFAS in England's drinking water regulations — moving from the current DWI guidance framework to a formal regulatory standard.
The plan also covers restrictions on new PFAS uses, cleanup liability for contaminated sites, and improved monitoring of PFAS in rivers and groundwater. It represents a significant shift from the previous position of monitoring and guidance towards active remediation and legal enforcement.
Scotland, Wales and Northern Ireland have separate regulatory frameworks but are engaged in similar monitoring programmes and are expected to align with stricter limits as they are set.
What Are Water Companies Doing?
Following the March 2025 DWI guidance, all water companies in England and Wales have been required to expand their PFAS monitoring programmes and update their risk assessments. Companies whose source waters sit in Tier 2 or Tier 3 are required to accelerate treatment investment.
The primary treatment technologies for PFAS removal are:
- Granular Activated Carbon (GAC): The most widely deployed solution. Large tanks of activated carbon adsorb PFAS compounds onto their surface as water passes through. Highly effective for PFAS removal, though spent carbon must be replaced or regenerated — creating an ongoing operational cost.
- Ion Exchange Resins: Single-use or regenerable resins that selectively bind PFAS compounds. More effective than GAC for shorter-chain PFAS, which are harder to remove by adsorption alone.
- Reverse Osmosis (RO): High-pressure membrane filtration that removes a very high percentage of dissolved contaminants including PFAS. More energy-intensive and expensive to operate at scale but delivers the lowest residual concentrations. Used where source water is heavily contaminated or for blending.
These treatment systems represent significant capital and operational investment — and they are now an active procurement category across AMP8.
PFAS treatment is one of the fastest-growing procurement categories in the water sector. Water companies are procuring GAC systems, ion exchange resin contracts, RO membrane installations, monitoring equipment, and PFAS testing laboratory services across their AMP8 programmes. Specialist treatment technology providers, analytical labs and civil contractors delivering treatment works upgrades are all seeing increased demand. The Water Industry Hub directory covers providers across these categories.
Should You Be Concerned About Your Tap Water?
Based on current evidence and DWI monitoring data, treated tap water in England and Wales is within regulatory limits for PFAS. Drinking filtered tap water remains the safest, cheapest and most environmentally sustainable way to stay hydrated — switching to bottled water does not guarantee lower PFAS exposure and generates significant plastic waste.
If you want to reduce PFAS exposure further, NSF-certified point-of-use filters (reverse osmosis or some activated carbon filters certified for PFAS reduction) can reduce concentrations in tap water at the household level. Standard pour-through filters (such as Brita-type) are less effective for PFAS — check the specific product certification rather than assuming any carbon filter provides PFAS protection.
The most important step you can take is to stay informed: the regulatory picture is changing quickly, and the forthcoming consultation on statutory PFAS limits may lead to further changes in how companies are required to report and respond. The DWI publishes annual drinking water quality reports for each water company — these are public documents and include PFAS monitoring data.
PFAS in UK Drinking Water — Key Facts 2026
- 4,700+ PFAS compounds exist — all share the "forever" property of not breaking down naturally
- Sources: firefighting foam, industrial discharges, agricultural runoff, landfill leachate
- DWI guideline (March 2025): 0.1 µg/L sum of 48 named PFAS
- 35–37% of English and Welsh watercourses show medium or high PFAS risk levels
- London tap water study (Imperial College, 2026): PFAS detected but within safe limits
- UK Government published first PFAS action plan: 3 February 2026
- Statutory drinking water limits: under consultation — watch for 2026 regulatory update
- Treatment: GAC, ion exchange and reverse osmosis are the primary removal technologies
- PFAS treatment is now a major AMP8 procurement category across the sector
Track Water Treatment Technology Suppliers
GAC systems, ion exchange, membrane filtration, advanced treatment — find specialist suppliers across water quality and treatment in the Water Industry Hub directory.
Explore the Directory → AMP8 Intelligence →Sources: Drinking Water Inspectorate (PFAS guidance, March 2025); UK Government PFAS National Plan (3 February 2026); Imperial College London London tap water PFAS study (2026); Climate Fact Checks / Environment Agency (watercourse PFAS levels, England and Wales); Fieldfisher PFAS UK Regulatory Snapshot (November 2025); Royal Society of Chemistry; Veolia Water Technologies (PFAS treatment guide). Independent analysis by Water Industry Hub. This article is informational only and does not constitute health or regulatory advice. Always refer to the DWI and your water company for current supply-specific data. Water Industry Hub is an independent intelligence and directory service and is not affiliated with any water company or regulator.