Thames Water has received multiple bids for the struggling business which has warned that it could run out of cash by next year.
Castle Water, a Scottish utility firm co-owned by Conservative Party treasurer Graham Edwards, is understood to have made an offer for Thames Water ahead of a deadline for potential investors.
Infrastructure investor Covalis, supported by French firm Suez, had also reportedly thrown its hat in the ring, in a deal which could lead to the break-up of the debt-ridden water giant.
Thames is the UK’s biggest water company and one in four people in the UK rely on the firm for their supply.
The ailing water firm is saddled with debts which, it admitted, will swell to nearly £18bn next March.
Customers are facing a steep rise in their water bills. In July, Thames told the industry regulator Ofwat that it wanted to increase annual bills by 23% between 2025 and 2030.
Since then, Thames has said it needed to raise them by 53%.
The BBC understands there are up to six parties interested in taking a stake in Thames Water.
This would happen once the firm’s existing investors have agreed how much of the debt owed to them they are willing to write off and there is greater clarity on by how much Thames can raise household bills.
Other possible buyers include Brookfield Asset Management, the Canadian investment giant chaired by the former Bank of England governor Mark Carney and Hong Kong’s CKI which already owns a stake in Northumbrian Water.
Thames Water, Covalis and Suez have been contacted for comment.
