Leading voices: Munira Wilson MP

18 May 2026

The Member of Parliament for Twickenham talks to Jo Caird about campaigning for a statutory limit for PFAS concentration in drinking water

Editor’s note (May 2026): This interview took place in December 2024 and first appeared in the Spring 2025 print edition of The Environment. Following the publication of the House of Commons Environmental Audit Committee’s report on PFAS last month and the government’s PFAS Plan in February, we publish it on our website for the first time. References to legislation and policy reflect the position at the time of interview unless otherwise stated.

On 05 November 2024, the Liberal Democrat MP for Twickenham, Munira Wilson, stood up in the House of Commons to introduce a Private Members’ bill to regulate levels of per and poly-fluoroalkyl substances (PFAS) in our drinking water. These chemicals, Wilson told a rather sparsely attended Commons Chamber, are found in thousands of everyday products, relied upon for their stain, water and heat-resistant properties. Because PFAS do not break down in nature, she continued, they persist in the environment, including in our bodies, with negative health implications ranging from cancer to reduced fertility.

There is already technical guidance for water companies, in effect from the start of this year, which makes it clear that they will be expected to monitor for and enforce a limit of 100 ng/L for a new cumulative sum of 48 PFAS. This is a tightening on the previous guidance, a limit of 100 ng/L for each of the 48 individual types of PFAS.

Responding via email in December 2024 to questions sent by The Environment, Wilson says that she welcomes the update but believes that, “we can, and must, go further. My bill would introduce a statutory limit for PFAS concentration and require water companies to monitor and limit PFAS levels in drinking water supplies.

“Despite the alarming health risks, there’s currently no legal limit on the amount of PFAS present in our drinking water – only guidance that the water be ‘wholesome’. I think it’s fair to say that the presence of carcinogenic ‘forever chemicals’ makes our water far from wholesome, and instead akin to a chemical cocktail – one that must be regulated by law.”

Trouble at Teddington

Wilson first became aware of the issue of PFAS when the Royal Society of Chemistry (RSC) got in touch about a proposal by Thames Water for a new river abstraction on the River Thames in her constituency. The proposal, designed as a drought resistance measure for use in periods of prolonged dry weather, would remove up to 75 million litres of water per day for drinking water from the Thames upstream of Teddington Weir. This water would then be replaced with recycled water from Mogden Sewage Treatment Works in Isleworth. It was this aspect of the proposal that gave Wilson pause.

“Thames Water has consistently maintained that, under these controversial water recycling proposals, the effluent that it pumps into the river at Teddington would be of the same quality as the river water itself,” she says.

“Yet we know that treated effluent contains a host of compounds and chemicals that we’ve not been assured would be filtered out, including pharmaceuticals and forever chemicals, which don’t break down in the environment and are known to cause health complications in humans and wildlife. As my team and I researched further into forever chemicals, we became more and more concerned.”

As the LibDem spokesperson for education, children and families, Wilson says that she is “particularly worried about evidence that PFAS are linked to developmental delays in children”. Speaking in the House of Commons, she referred to studies that suggest that children exposed to PFAS are at an increased risk of low birth weight, weaker bones and immune resistance to vaccinations.

Munira Wilson MP Factsheet

The Liberal Democrat politician Munira Wilson was elected Member of Parliament for the West London constituency of Twickenham in December 2019. She replaced Vince Cable, who had held the seat for the Lib Dems since 1997, barring a period of two years when it was held by the Conservatives. She was appointed Liberal Democrat Spokesperson for Education, Children and Families in 2021. Wilson was re-elected as MP for Twickenham at the general election in 2024.

Wilson began her working life as a tax consultant with Ernst & Young (now EY), before coming to work for the former LibDem MPs Sue Doughty and Nick Clegg. She served as a LibDem councillor on Richmond upon Thames London Borough Council between 2006 and 2010.

Before she became an MP, Wilson worked as a parliamentary lobbyist, for the charities Save the Children and Beating Bowl Cancer, the pharmaceutical company Novartis and the science and technology company Merck.

She grew up in London and studied French and German at the University of Cambridge.

International examples

Many of the studies on the impact of PFAS on human health have been published in the United States, one of the jurisdictions that Wilson believes the UK should look to as an example of how to regulate in this space. In April 2024, the United States Environmental Protection Agency (EPA) introduced a limit of 4 ng/L for two PFAS chemicals – PFOS and PFOA – and a limit of 10 ng/L for a further three. Doing so, the EPA announced at the time, would “reduce PFAS exposure for approximately 100 million people, prevent thousands of deaths, and reduce tens of thousands of serious illnesses”.

Wilson also pointed to the EU, where from January 2026, member states will have to ensure that PFAS levels do not exceed 0.5 µg/l, with the levels of 20 named PFAS to be below 0.1 µg/L each. “There are many examples we can look to,” says the MP. “What my bill is proposing isn’t radical action.”

Source control

That said, Wilson is well aware that regulation of PFAS in drinking water is only one of piece of the puzzle. She was pleased to see the recent ban, from this July, of certain PFAS in firefighting foams, but wants to see “further action” that will address these chemicals at source.

“As we discover more and more health risks from PFAS chemicals every day, it’s clear they must be regulated more tightly as a chemical group, not as and when the threat is slowly identified,” says Wilson. “The previous Conservative government sat on their hands and ignored this crisis.”

She lays the blame partly at the door of Brexit, which saw the UK leave REACH, the main EU legislation for the regulation of chemicals in the EU, adopting UK REACH in its place. “Our response to the growing threat of PFAS has moved at a snail's pace and we have fallen behind,” says Wilson. “Not a single restriction on a harmful substance has been adopted since the UK left EU REACH in 2021, other than PFHxS following its ban internationally.

“This is in part due to the UK’s Health and Safety Executive no longer having access to the world’s most comprehensive chemical registration database held by the European Chemical Agency. We now must go through duplicate processes to process these chemicals for regulatory decision making. There’s a clear need for alignment, not least to avoid the UK becoming a dumping ground for products containing chemicals banned in the EU so I do hope the government will keep its manifesto promise to see this through.”

Responding to Wilson’s call for action on PFAS, a Defra spokesperson said: “UK drinking water standards are of an exceptionally high standard and among the best in the world. Water companies are required to carry out assessments and sampling and there is no evidence supplies contain more than the guidance value of 0.1 micrograms set by the Drinking Water Inspectorate in 2024.

“This government is committed to protecting the environment from risks posed by chemicals. We are investigating the restriction of PFAS in firefighting foams and also progressing work to consider further measures relating to PFAS.”

Along with regulating the use of these chemicals, Wilson supports the call, made by Marcus Rink, chief inspector of the Drinking Water Inspectorate (DWI), and Philip Duffy, chief executive of the EA, at British Water’s conference in November 2024, for the government to introduce a strategy to address chemical pollution. Such a strategy would be “a very welcome step”, says Wilson. “Years of inaction on this subject has already unleashed untold harm upon people and the environment, but this is not a hopeless cause.”

Wilson’s bill was scheduled to receive a second reading at the end of January, but as is the case for the vast majority of private members’ bills, it was not debated by MPs and therefore hasn’t made it through to the next stage of the legislative process. Despite this apparent setback, however, Wilson remains undeterred in her ambition to address the challenge of PFAS: “I was really pleased that my bill had cross-party support, which shows the appetite for change amongst MPs. This was just the first step in a campaign to ensure that we have a country where we can safely enjoy nature, and preserve people’s health, for generations to come.”

Looking ahead, Wilson says that she will be pursuing “further legislative opportunities to keep pressing ministers on this topic, not least as the government brings forward legislation relating to the water industry”. In January, for example, the MP added several amendments to the Water (Special Measures) Bill, including calling for a larger strategy to tackle PFAS pollution up-stream at its source. Whether or not they make it into law, as that bill makes its way through parliament, we’ll just have to wait and see.

For the moment, Wilson is clearly fired up: “Everyone deserves access to safe drinking water. Yet, for too long, water companies have had carte blanche to pollute our precious water supplies. If we don’t act now, these dangerous chemicals could harm the health of generations to come.”

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This article appeared in the Spring 2025 print edition of The Environment. Become a member of CIWEM today to gain access to the quarterly magazine, as well as digital access via MyCIWEM. Non-members can also access the monthly The Environment digital newsletter.

Jo Caird is editor of The Environment