Households are to see almost £150 million taken off their water bills after 11 water suppliers have been hit by fines, regulator Ofwat has announced.

Among the fined companies, Thames Water and Southern Water were said to have performed the worst and will have to return almost £80m to customers, according to Ofwat.

Anglian Water, Northumbrian Water and Yorkshire Water, among others, also face fines following the regulator's recent enforcement cases, as part of an ongoing investigation into wastewater treatment works.

“When it comes to delivering for their customers, too many water companies are falling short, and we are requiring them to return around £150 million to their customers," said David Black, the chief executive of Ofwat for England and Wales. “We expect companies to improve their performance every year; where they fail to do so, we will hold them to account.

“All water companies need to earn back the trust of customers and the public...