London tap water: 'Forever chemicals' present but 'within safe limits', study finds

Worried about 'forever chemicals' in your London tap water? A massive new study reveals these persistent pollutants are indeed present, but before you panic, experts say the levels are well within safety limits. Phew!

This major analysis, led by Imperial College London, is the largest of its kind for a UK city, offering vital reassurance.

What Are 'Forever Chemicals' Anyway?

Often called 'forever chemicals', PFAS (per- and polyfluoroalkyl substances) are a group of tough, long-lasting manufactured chemicals. They are used in countless products, from non-stick pans to food packaging.

These chemicals break down very slowly, meaning they can build up in our environment and bodies over time. There have been concerns about their potential long-term health impacts, like links to certain cancers and thyroid disease.

Tiny Amounts, Big Study

The study, conducted in 2024, took a 'citizen science' approach. Researchers sent sample kits to 89 households across 28 London Boroughs, collecting nearly 8,000 measurements. They also tested 12 public drinking water fountains.

Out of 38 PFAS compounds tested, 11 were detected.

Crucially, all individual PFAS compounds were found at concentrations ranging from 0.6 ng/L to 6.0 ng/L. This is well below the 10 ng/L 'Tier 1' threshold set by the UK Drinking Water Inspectorate (DWI).

The total PFAS in any single sample ranged from 3 ng/L to 35 ng/L. This too was safely within the DWI’s 100 ng/L low-risk threshold.

These levels are also well within EU Drinking Water Directive limits, providing further peace of mind.

Experts Weigh In

Dr Alexandra Richardson, lead author from Imperial College London's School of Public Health, wants to allay fears.

She said: "People might be concerned to know that these chemicals are present in our drinking water, but it's crucial to understand the amounts we're talking about are tiny." She explained further: "To put these levels in context, 4 nanograms per litre is equivalent to dissolving one sugar cube in 400 Olympic-sized swimming pools of water."

Professor Leon Barron, another principal investigator, highlighted the quality of UK water.

He commented: "We have some of the best municipal tap water quality in the world. Only about 20% of the tolerable weekly intake of PFAS came from tap water."

What's Next?

While the findings are encouraging, experts stress the need for continued independent monitoring. This is essential to ensure safe limits are never breached and to understand the long-term effects of these chemicals.

Dr Frédéric Piel from Imperial added that new PFAS compounds are still being developed. He stressed: "It is essential to keep monitoring their presence in the environment and in our bodies to study potential long-term health risks."

Imperial and partners launched the UNSaFE project in 2025. This initiative will develop new testing methods and investigate how PFAS persist in the environment.

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OFFICIAL SOURCE VERIFICATION: This report is based on official data from University Newsroom. Document: Major survey of London tap water shows 'forever chemicals’ within safe limits Source Link: [Read the official report from University Newsroom](https://www.imperial.ac.uk/news/articles/2026/major-survey-of-london-tap-water-shows-forever-chemicals-within-safe-limits/)