The water company is inviting experienced big firms to prequalify for one or more delivery partner roles.
These involve establishing a Public Private Partnership-type financing model to deliver the huge civil engineering project.
Interested firms will be expected to have annual fee income of more than £100m.
The Thames Tunnel project will involve constructing a 30km, 7m diameter interceptor sewer and around 35 combined sewer outfall shafts.
It has already started design work for the project, which is expected to be completed by 2020.
Thames Water is searching for one or more delivery partners to provide legal, financial, and commercial advice and develop the PPP style contract model in two distinct phases.
Phase 1: Develop a detailed approach for delivering the project through an ISP, including structuring the necessary financial and contractual arrangements.
Phase 2: Develop ISP procurement documentation, invite bids and select the preferred ISP bidder.
Thames Water will formally invite tenders for the job during September/October 2010.
Firms wishing to be considered need to contact the Thames Water’s Reading office or email email@example.com no later than 15.9.2010.