Water company Severn Trent (STW) paid £4.6m to the Environment Agency to settle pollution cases in the past year, the highest total of any provider.
Offences included unauthorised sewage discharges into the River Blythe in Solihull, Broadway Brook in Evesham, Worcestershire, and Marehay treatment works in Ripley, Derbyshire.
In total, a record £8.5m was secured from water companies during the 2025-26 financial year, the government said.
“Our focus is always on preventing pollutions before they happen, but when things do go wrong, we act quickly, take ownership and put things right,” said a STW spokesperson.