Cornwall has seen more water pollution incidents than any other local authority area in England, new figures show.

The Environment Agency recorded 1,278 incidents in the area over five years, making it the only place to top 1,000 cases, data obtained by Radar has revealed.

Laurence Couldrick, chief executive of the Westcountry Rivers Trust, warned of the impact of pollution on Cornish rivers and seas, given their “economic and environmental importance”.

He urged water companies to clean up their act in the south west but said agriculture and other sources are also to blame.

Larger local authorities were most likely to have suffered water pollution but three cities – Bradford (447 incidents), Leeds (361) and Birmingham (343) – also made the top 20.

Across England, nearly 36,000 category one to three water pollution incidents were recorded between 2018 and 2022.

Of these, 246 were classed as ‘major’ incidents – the most serious category – while 1,286 were ‘significant’.

The water industry has come under particular scrutiny for how it records pollution events.

The figures show the number of cases stemming from water companies is on the rise – from 1,922 in 2018 to 2,213 last year.

This week, an investigation by BBC Panorama suggested United Utilities, a water company in the north west of England, wrongfully downgraded 60 incidents to the lowest possible category, meaning they caused no environmental harm.

United Utilities “strongly rejects” the claims.

Water pollution can also come from other sources, such as agricultural run-off or industry and manufacturing.

The Rivers Trust, a charity working to protect waterways in the UK, said: “People are rightly demanding that we restore our water bodies to a state of good health and resilience.”

Tessa Wardley, director of communications and advocacy at the charity, called Panorama’s findings “extremely concerning”.

She said “any pollution affecting rivers must be taken seriously”, noting that not a single river in England is classed as being in good health.

A spokesperson for Water UK, a trade association, said: “Although this data reveals that two-thirds of all water pollution incidents had nothing to do with water companies, the industry takes its role in reducing pollution very seriously.”

They said serious incidents have fallen by more than a third since 2011.

“Companies are now proposing to invest £96 billion, the highest on record, which will include upgrades to sewage treatment works and an overhaul of our sewer network,” they added.

An Environment Agency spokesperson said: “The number of pollution incidents caused by the water industry is unacceptably high. We expect water companies to significantly reduce them, and to report them to us quickly.

“We will not hesitate to take enforcement action where necessary and have secured over £150 million in fines from the water industry since 2015.”