The UK is estimated to have at least 8,000 illegal waste sites, containing approximately 13m tonnes of rubbish, research has revealed.

The scale of the criminal dumping means at least £1.63bn of landfill taxes have been avoided, according to an analysis of data from the satellite company Air & Space Evidence, shared with the Guardian and Watershed Investigations.

“The big concern is that along with avoiding landfill tax, they are also avoiding the regulations that control what can go in landfill and ensure that people and the environment are protected,” said Prof Kate Spencer, a landfill expert at Queen Mary University of London.

“There’s nothing to stop any pollutants being washed into nearby rivers or soils. We also know that illegal waste disposal can create a big concern for local communities in terms of smell, eyesore and littering.

“We have illegal waste sites in Essex that regularly catch fire with the potential to harm local air quality and human health.”

The high estimated number of illegal sites suggests the authorities are barely scratching the surface of the crisis. In the year 2024-2025, the Environment Agency (EA) shut down 743 illegal waste sites in England and the agency’s waste investigations data showed 1,143 ongoing cases of illegal dumps.

Yet Air & Space Evidence said the EA was not interested in using its intelligence tool, which could help inform law enforcement where to look for illegal waste sites.

“When we spoke with the Environment Agency there was much interest at the technical level, but at the management level there was no interest,” said Ray Harris, the company’s director and emeritus professor of geography at University College London.

“From the outside, this looks like a fear of finding out. If the Environment Agency finds more illegal waste sites then they feel they will have to do something about them. So, they would rather not know.”

Air & Space Evidence says its detection tool has been tried out by authorities in New Zealand, where law enforcement confirmed waste at all 125 suspected landfill sites, 58% of which were previously unknown to them.

The estimated number of sites in the UK was calculated by examining detailed satellite images of areas including London, Brussels and Bucharest – as well as parts of New Zealand – and using that to model the average number of sites across the country.

The figure of 8,000 sites is at the lower end of the estimate; the researchers found there could be as many as 13,000.

In October, a House of Lords report highlighted widespread failings within the EA, the poor performance of its joint unit for waste crime, and the limited engagement of police in addressing what has been dubbed “the new narcotics”.

“Despite the scale and seriousness of the crimes, raised by the members of the public in many cases, we have found multiple failings by the Environment Agency and other agencies, from slow responses to repeated public reports (as in the case of Hoad’s Wood, Kent) through to a woeful lack of successful convictions,” Lady Sheehan, chair of the Lords’ environment and climate change committee, said in her report.

Criminals dumped 35,000 tonnes of rubbish in Hoad’s Wood, saddling taxpayers with a £15m cleanup cost, and in Oxfordshire, the Kidlington site is thought to hold several hundred tonnes of household and commercial waste. According to the committee, there are six sites of similar or greater size than these, which they say points to a “fundamentally broken system”.

EA waste crime data shows ongoing cases have been open for an average of four years. There are 13 cases that have been open for 11 years, some involving the burning of hundreds tonnes of asbestos.

“Without regulation it will get worse,” said Spencer. “I suspect the legal mechanisms are there to regulate it, but it comes down to resources and identifying who is responsible.

“We have a polluters pay system, but if you can’t find the culprit, who pays to clean up these sites?”

The scale of the problem, losses in revenue and the cost of cleaning up has led some to question the overall benefits of the landfill tax.

“The landfill tax is significant and it’s leading to these loopholes,” said Paul Brindley, a senior lecturer at the University of Sheffield, who said tax revenues have been falling in the past decade.

“The cost of clearing up far outweighs the money we’re receiving from landfill tax and we’re missing all these unknown sites. Is the landfill tax counterproductive and creating an environmental catastrophe that will only get worse?” he said.

An Environment Agency spokesperson said: “Illegal waste dumping is appalling, and we work tirelessly to protect the environment and communities from it.

“Investigations can be multilayered and complex as we look to bring rogue operators – often from the criminal underworld – to justice.

“Last year alone our dedicated teams successfully stopped activity at 743 illegal waste sites, and we’re doubling staff in our joint waste crime unit to help crack down on these miserable crimes.”

Shlomo Dowen of UK Without Incineration Network said: “These illegal waste sites are known to local people.

“They often raise the alarm to councils and the Environment Agency and when no action is taken they stop reporting it, because they lose faith in the system and give up on the expectation that the EA is capable of protecting them and the environment.”