A water company repeatedly dumped millions of litres of raw sewage illegally into one of England’s most famous lakes over a three-year period, the BBC can reveal.

More than 140 million litres of waste were pumped into Windermere between 2021 and 2023 at times when it was not permitted, our analysis shows, and United Utilities failed to report most of it.

It means the company’s illegal dumping of sewage into the lake went on for far longer, and was far more extensive, than was previously known.

Credit: Rick Barrett

United Utilities said some of its sewage releases into Windermere were “potentially non-compliant” but that it self-reports “over 94% of potential pollution incidents to the Environment Agency”.

Matt Staniek, a campaigner against sewage pollution and founder of Save Windermere, said Windermere was “the jewel in the crown of the Lake District National Park, and it’s being used as an open sewer”.

It is sometimes necessary to release sewage into rivers and lakes to stop the wastewater system from being overwhelmed by heavy rain but this pollution can damage the environment, causing harmful algal blooms and even killing fish.

In January this year – after BBC Panorama revealed the company had downplayed the severity of dozens of pollution incidents, some involving Windermere – United Utilities retrospectively reported some discharges into the lake from October 2023 onwards.