Thames Water is facing crunch talks over its finances amid mounting concerns about its ability to service a debt mountain which stands at more than £14bn.

Sky News has learnt that Thames Water, which is privately owned and employs about 7,000 people, has in the last few weeks hired Rothschild, the investment bank, and the law firm Slaughter & May to explore financing options for the company.

The appointment of the advisers has taken place against a backdrop of growing public and political fury about the company's dire record at preventing leaks and raw sewage discharges.

Thames Water serves nearly a quarter of Britain's population, with 15m customers across London and the Thames Valley.

Industry sources said the government and Ofwat, the industry regulator, were aware of growing concerns about its financial position.

A Thames Water spokesperson said: "It's normal course of business to appoint advisors to support the funding of our investment programme."

Sarah Bentley, who joined as chief executive in 2020, is overseeing an eight-year plan to transform the company's operating and financial performance.

Ms Bentley recently declared that she was "heartbroken" about the company's historical failings, blaming "decades of underinvestment".

It has been fined numerous times, and is facing a deluge of regulatory probes.

In 2021, it was hit with a £4m penalty for allowing untreated sewage to escape into a river and park, while in August 2021, it was ordered to pay £11m for overcharging thousands of customers.

The range of financing options to Thames Water's board - which is chaired by the former SSE chief Ian Marchant - beyond seeking new equity investors or attempting to raise additional debt was unclear this weekend.

Nearly £1.4bn of the company's bonds mature by the end of next year, with Ofwat price controls meaning water companies have little scope to generate additional income.

In an investor update published last September, Ms Bentley said that "the difficult external environment has increased the challenge of our turnaround".

"We've…made progress improving some of our performance metrics with a 43% reduction in customers' complaints, as well as reductions in total pollutions and sewer flooding incidents.

"That said, there's still a long way to go, and the recent drought affected progress on water metrics following a spike in leakage caused by exceptional dry ground conditions."

Last July, the company said it had agreed with shareholders the injection of £500m of new equity funding, with a further £1bn expected to be delivered by the end of next year.

Thames Water is owned by a group of pension funds and sovereign wealth funds, some of which are said to be sceptical about delivering additional funding referred to in the company's last financial update.

Its largest shareholder is Ontario Municipal Employees Retirement System (Omers), a vast Canadian pension fund, which holds a stake of nearly 32%, according to Thames Water's website.

Others include China Investment Corporation, the country's sovereign wealth fund; the Universities Superannuation Scheme, the UK's biggest private pension fund; and Infinity Investments, a subsidiary of the Abu Dhabi Investment Authority.

Hermes, which manages the BT Group pension scheme, is also a shareholder.

The additional shareholder funding formed part of a £2bn expenditure increase, taking its total spending during the current five-year regulatory period to £11.6bn.

In its September update, Thames Water said shareholders had "further evidenced their support for [Thames Water] and its business plan through an Equity Support Letter where the shareholders have committed to hold investment committee meetings (for their respective institutions) as a path to obtaining approval (in the discretion of the investment committee) for funding their pro rata share of conditional commitments in respect of the further £1bn of additional equity which is assumed in TWUL's business plan".

"Whilst this is not a legal commitment to fund, is subject to conditions and is dependent on governance arrangements between shareholders, given that [Thames Water] and its shareholders are currently engaged in a collaborative process to agree and facilitate such equity commitments, the [Thames Water] board believes it is reasonable to incorporate this additional £1bn of equity funding in its assessment."

The company has not paid its owners a dividend for nearly six years, and some shareholders are said to be increasingly keen to offload their holdings.

"In the scenario where sufficient equity commitments and/or funding were not forthcoming, [Thames Water], at that point, could revise its business plan to fit with then available funding, and adjust total expenditure down accordingly," the company said last autumn.

Thames Water is due to complete a consultation with Ofwat later this month on the establish of a Water Resource Management Plan, setting out how it will meet customer needs until the 2050s.

"Customers depend on companies to provide reliable water supplies," David Black, the regulator's chief executive, said.

"This requires companies to prepare properly for population growth and the impact of climate change."

Thames Water is not the only major water company to face questions about its financial resilience and operational track record.

Ofwat has also been in talks with others, including Southern Water and Yorkshire Water, in recent years about strengthening balance sheets amid performance issues.

There have been growing calls for the industry's ownership model to be overhauled because of the disquiet over lavish executive pay and the failure of companies to prevent waste and sewage contamination.

These ongoing controversies have fuelled demands for the consideration of mutual ownership structures, which would prohibit returns to shareholders and guarantee that profits would be reinvested in improving the sector's dire performance, while upgrading water infrastructure assets.

In total, tens of billions of pounds have been handed to shareholders in water utilities across Britain since privatisation, stoking public and political anger given the industry's frequent mishaps.

A spokeswoman said an update on Thames Water's net debt position would be published in its annual report in July.