Wessex Water defends £80,000 pay rise for CEO Ruth Jefferson

But Matt Wheeldon, Wessex Water’s director of infrastructure, said: “The environmental impact from storm overflows is tiny.”

He pointed to EA data, which suggests Wessex Water was responsible for rivers not reaching “good” ecological status in about 25% of cases, with agriculture and rural land management having a much bigger impact.

“Less than 1% of the reasons are down to storm overflows,” added Wheeldon.

The statistics suggest the release of treated sewage is a much bigger environmental problem because of the excess nutrients and chemicals it contains.

The EA classifies the rivers Avon, Frome and Severn as in “moderate” ecological status, based on assessments from 2022.

Wheeldon denied that river water quality had got worse.

“For the past 30, rivers have got better,” he said. “There’s plenty of scientific papers written about how ecology has recovered.

“Enjoy your river, it’s cleaner than it’s ever been, it’s going to get cleaner, but it’s never safe to ingest,” he added.