From BBC
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BBC environment correspondent
Reporting fromWindermere
Becky Dale
BBC Verify
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Sewage spilled illegally into England’s largest lake on a record number of days last year, an analysis of water company data by campaigners suggests.
The analysis, which the BBC had exclusive access to, used United Utilities operational data to establish when the company was discharging sewage into Windermere when it should by law have been treating some of it.
The campaigners from Windrush Against Sewage Pollution (WASP) and Save Windermere identified 140 illegal spill days in 2024, more than in any of the three previous years.
United Utilities told BBC News that the campaigners’ findings were “inaccurate” and some of the data “erroneous”.
The company declined to put in writing, despite repeated requests, any specific examples of mistakes or omissions.
Regulators Ofwat and the Environment Agency are both currently investigating United Utilities operations.
Last week the Environment Agency said United Utilities had spilled 77,817 times in 2024, the highest figure of all England’s water companies.
Many of the spills will have been legal. All water companies are legally allowed to discharge raw sewage to stop the network getting overwhelmed and this now happens regularly during periods of heavy rain.
But almost all pumping stations and treatment plants operate under an environmental permit which specify that they must process or “pass forward” a certain amount of sewage and rainwater before spilling starts.
The campaigners cross-referenced United Utilities datasets showing when an asset was spilling against how much sewage it
