The environmental campaign group submitted Freedom of Information (FOI) requests to all 22 Welsh local authorities, asking for their contaminated land registers. Of these, 18 councils responded.
The information provided, combined with Friends of the Earth Cymru’s own analysis of publicly available data, uncovered 45,157 potentially contaminated sites.
Because four councils failed to respond, the group warns that the true figure is likely to be higher.
Land is considered as contaminated when hazardous substances – such as heavy metals, hydrocarbons, asbestos, pesticides or industrial chemicals – are prevent at levels that pose a risk to human health, the environment, property or water resources.
The contaminated sites identified by the investigation included old industrial areas, landfills and quarries.
Kirsty Luff, Friends of the Earth Cymru spokesperson, said: “We must make sure the land beneath our feet is safe for people and wildlife. It’s shocking that so much land could be contaminated and yet isn’t being properly inspected.
“People in Wales deserve to know whether the places where they live, work, and play are free from pollution.
“Without proper inspection, these sites remain a mystery – a hidden toxic legacy from our industrial past that could still be harming communities today.”
Few inspections have been carried out
Despite the scale of the issue, only 82 sites in Wales are officially designated as contaminated.
Campaigners say this points to a major gap between what is known and what is being properly investigated.
Of the 22 councils, only six provide a complete public register of contaminated land online. 15 councils have an inspection strategy in place.
Friends of the Earth Cymru said that the four councils that did not make their registers public nonetheless said they had identified land that should appear on them.
In one case, a council stated on its website that no contaminated sites had been identified, but later revealed to the group that it had in fact logged 18 likely sites – though it lacked the funding to carry out investigations.
‘This issue must not be ignored’
Friends of the Earth Cymru is urging both the Welsh and UK governments to provide councils with the funding and resources needed to properly identify, assess and clean up contaminated land across the country.
Luff added: “Councils are legally required to identify and assess contaminated land, but they don’t have the funding, resources, or political support to do the job. That’s why we’re calling for a public inquiry and urgent action from both the Welsh and UK Governments.
“This issue must not be ignored – the longer the delay, the greater the risk to our health, the environment and future generations.”
In July 2025, a new scheme began trials in south Wales to tackle farm plastic pollution and reduce the amount of waste going into local rivers.
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