Reynolds said on Tuesday that she did not want a scenario where Thames Water customers had to “pick up the bill for the company’s failures”.

She told reporters that the government “stands ready for all eventualities”, including temporary nationalisation.

Speaking in the House of Commons, Reynolds said she had “three particular concerns about the proposal: the unfair cost to customers, delays to vital infrastructure investments, and delays to environmental improvements”.

“There is an expectation in the proposal for customers to fund and therefore bear an undue cost for investment in the company,” she said.

“In addition, I’m not convinced about the proposal’s request to reduce performance standards and about the significant delay to vital infrastructure investments needed.”

She added she was “concerned that the long-term resilience of the water and wastewater systems may not be adequately protected”.

However, a spokesperson for L&VW said the group was “confident that our plan is by far the fastest route to improve outcomes for customers and the environment, without any government funding or any cost to taxpayers”.

The proposed deal was a “long-term solution that recognises the full extent of Thames Water’s problems”.

“All other routes offer significantly worse outcomes for customers and the environment. Our proposals do not anticipate any increase in customer bills beyond those set out by Ofwat,” they added.

“Creating further delay and transferring risk to the taxpayer with special administration is not the right answer. It will only delay the process of fixing Thames Water.”