Monday 22nd June, 2026
The range of chemicals used every day for personal, domestic, industrial and agricultural purposes in the UK is immense.
Many of these, along with chemicals from the past, end up in rivers. They come through overflows, from industrial discharges, directly through drains or washed off fields and yards. Others arrive via road runoff or seep out of contaminated land fill sites and abandoned mines.
Public awareness of chemical pollution in rivers has been rising over the past few years. It is widely known that PFAS (forever chemicals) can now be found in nearly all of us, their main vector being drinking water.
The effects of these and other substances both to us and the environment are well documented. They can damage our organs, increase our cancer rates and affect our development. In aquatic life they lead to a loss of biodiversity, disrupt food chains and change the ecology of rivers.
And with climate change leading to more frequent, extreme rainfall events that release more chemicals into rivers (as well as re-mobilising those stored in sediment), this is a problem that is likely only to get worse.
Wales has a rich industrial history that includes many now-abandoned mines, just one of the sources of chemical pollution in rivers. (photo: iStock.com/Robert Thornley)
No understanding of the scale
Despite this awareness, we still do not have an accurate picture of the extent of chemical pollution in Wales.
Our main concern was that in the absence of chemical monitoring in Wales, 90% of Welsh waterbodies were simply assumed to be in High Status and that over half of the waterbodies in Wales have no chemical monitoring data at all. Meanwhile, passive monitoring programmes and individual studies on rivers show a high prevalence of a broad range of chemicals.
We have no chance of resolving the issue when we do not even have a basic understanding of its extent.
The new Government’s stance
The new Government has a job on its hands. In its manifesto, Plaid Cymru pledged to work to ensure every water body in Wales achieves a minimum ‘good’ status (although it didn’t say by when) and to support a science and evidence led approach.
So, the first logical step of that will be to strengthen chemical monitoring across Wales.
Also welcome is the new Government’s desire to align with Europe, where chemical standards in the last month have been updated with its list of water pollutants to include newly identified substances harmful to the environment and to people.
These additions included not only certain PFAS, pesticides and pharmaceuticals but for the first time, microplastics, indicators of antimicrobial resistance, and sensitive groundwater ecosystems. Following our departure from the EU, tightened chemical standards at wastewater treatment works in the UK have also not been adopted.
Who pays?
A 2025 YouGov survey quoted in a Senedd Research report on forever chemicals earlier in June showed that, understandably, 90% of people in the UK believe it is ‘very important’ to effectively control levels of PFAS in food, drinking water and the environment.
It is probably safe to assume they feel similarly about other harmful chemicals. But, who pays for that?
Plaid want to strengthen the ‘polluter pays’ principle but applying that to landfill sites and historic mines, for example, that were created decades ago will be quite a challenge.
Stopping chemicals at source
One of the key messages from Welsh Government’s Green Paper on water reform was prevention at source. It had a recurring theme that Wales should move away from relying solely on ‘end of pipe’ treatment by water companies and instead focus on preventing pollutants from entering the water environment in the first place.
Like Europe, this will mean tighter regulation and proscribing of the use of dangerous chemicals across all economic sectors.
The British Veterinary Association (BVA) has advised against routine but largely unnecessary preventative use of pet flea treatments. These often use fipronil and imidacloprid, two substances that are extremely toxic to aquatic life and have been proven to be cause pollution in rivers. (photo: iStock.com/Sergio Boccardo)
Behaviour change alone is unlikely to be effective
Some have called for societal behaviour change, for all of us to ask whether we really need to use a chemical product before doing so.
But reliance on that is likely to take too long and could lack the willingness to be effective.
One encouraging recent move was the British Veterinary Association (BVA) advising against routine but largely unnecessary preventative use of pet flea treatments that include fipronil and imidacloprid. These two substances that are extremely toxic to aquatic life and have been proven to be cause pollution in rivers.
A complete ban is now being discussed at Westminster, something that should be supported.
This approach needs to be adopted for other sectors too. Non-stick pans, for example, are a major source of PFAS but are still produced despite having effective alternatives.
Further devolution to help?
The recent veterinary case also highlights that some of the biggest and most urgent issues affecting Wales sit outside of Welsh Government control.
However, chemicals in the environment is a UK-wide problem that needs to be resolved across all devolved nations.
Implementing stronger Producer Responsibility principles will need some significant support and willing from Westminster but the first key step for Wales’s new Government is to move forward on water reform.
This would at least be a signal of an appetite to start dealing with the chemical pollution problem.