Water regulator Ofwat has confirmed that stricken Thames Water must appoint an independent monitor to oversee its progress until its credit rating is restored.

Thames Water must also build a business plan to turn around its performance and work towards an equity raise – meaning securing investment – as part of the regulator’s requirements.

The monitor will have access to the company’s financial information, and the appointment comes after Thames’ credit rating was downgraded twice by rating agencies in July.

The country’s biggest water supplier breached its licence agreements after losing its “investment-grade” credit ratings, which indicates whether its debt is of good or bad quality, and meaning it is even harder for the firm to borrow money.

It must now meet the commitments set by the regulator until it regains two investment-grade credit ratings.

Moody’s downgraded its rating for Thames to “junk” status on July 24, indicating that the credit agency thinks the utility company is likely to default on its debt and may add to its financial pressures.

And on July 31, S&P downgraded Thames Water’s Class A debt rating to BB and its Class B debt rating to B.

Thames Water is now in the grip of a funding crisis having built up more than £15 billion of debt, and with only enough money to continue trading until the end of May 2025.

It comes as Ofwat also proposed £168 million of fines for three of England’s biggest water companies for failing to manage sewage spills, including a £104 million penalty for Thames.

The fine for Thames Water came alongside a £47 million penalty for Yorkshire Water and £17 million for Northumbrian Water, as the first batch of results from its biggest-ever investigation into the industry.

The penalties relate to water firms’ management of their wastewater treatment and sewer systems, which have come under heavy criticism for releasing too much pollution into rivers.

Campaigners welcomed the multimillion-pound fines proposed for three water companies but warned the penalties highlight the “sheer state of disrepair” of the industry.

A spokesman for Thames Water said: “We note that Ofwat is minded to accept the undertakings we have proposed, but understand the need for them to consult before doing so.

“We remain focused on working with Ofwat to secure an investible PR24 determination (the outcomes framework for the 2024 price review), which is key to attracting equity into the business.”