Bazalgette Tunnel Limited, a newly created special-purpose company, is in line to own, finance and deliver the project.
Backers of Bazalgette Tunnel Limited include funds managed by Allianz, Amber Infrastructure Group, Dalmore Capital Limited and DIF.
Twelve parties were invited to tender with two competitive bids received in the final round.
Thames Water will manage the procurement for the infrastructure provider and select the contractors to build the project.
The infrastructure provider’s responsibilities will be to deliver the tunnel, including managing the contractors during construction.
The infrastructure provider will be independent of Thames Water and have its own licence from Ofwat.
The Thames Tideway Tunnel is required to tackle the discharge of untreated sewage into the tidal River Thames through central London and to significantly increase the capacity of the overstretched Victorian sewerage network.
The 25 km tunnel will stretch largely beneath the bed of the River Thames, from Acton in the west to Abbey Mills in the east. There it will join up with the Lee Tunnel, currently under construction by Thames Water.