Thames Water and other British water companies have said they need to raise bills by more than they had estimated, blaming new regulatory requirements and investment costs, regulator Ofwat said.

The UK’s water watchdog will allow companies to invest as much as £7 billion ($9.1 billion) more in the next five years to curb sewage spills and improve drinking water quality, a move that will require further raising bills for consumers.

Water bills will go up by more than previously thought over the next five years, to fund higher costs and more investment, the BBC understands. The regulator, Ofwat, is in the process of deciding how much customer bills will be allowed to rise.

Water companies are lobbying for bill rises of up to 84 per cent in the next five years in a fresh blow to customers. Firms including beleaguered Thames Water have applied to the regulator, Ofwat, to hike tariffs so they can upgrade their networks,