Thames Water has asked creditors for more time to pay back billions of pounds in debt, as the water company scrambles to keep itself afloat.

The UK’s largest water company said it had proposed an “interim” deal under which the deadline to pay off an unspecified portion of the £20bn of debt on its balance sheet would be extended from 2027 to March 2028.

The company, which serves 16 million customers across London and the Thames Valley, has been on the brink of collapse for several years after it became overwhelmed by debt. Its shareholders walked away in 2024, which in effect left the company under the control of its creditors, who are working out a deal to avoid bankruptcy.

The creditors gave Thames Water a separate £3bn lifeline in February last year to try to see it through negotiations on a deal to reduce its debts and inject more money.…