Thames Water plans to spend nearly £20bn fixing leaks and sewage spills under a new business plan sent to regulators.

The beleaguered water supplier, which has £18bn of debt, wants to spend £1.1bn more than previously thought under proposals sent to the regulator Ofwat, known as PR24.

It is battling to avoid a costly nationalisation, which would mean its lenders lose as much as 40pc of their money.

Shareholders last month said they would not give the company a promised £500m lifeline which had been part of a planned £3.75bn funding package designed to see the company through to 2030. 

Chief executive Chris Weston said: “Our business plan focuses on our customers’ priorities.  

“As part of the usual ongoing discussions relating to PR24, we’ve now updated it to deliver more projects that will benefit the environment. We will continue to discuss this with our regulators and stakeholders.”