The Abingdon reservoir in Oxfordshire could cost up to £2.2bn to build and would supply water to 15m people across the South East.
Consultants Arup and Binnies have already been appointed joint venture technical partners for the scheme and Costain has started clay compaction trials to understand the ground conditions at the site.
This fieldwork programme will help to inform an application for development consent in 2026.
If development consent is granted in 2028, construction is expected to start in 2029 for opening in 2040.
At the event, Thames Water will update contractors and investors on the development of the reservoir, including the company’s commercial and procurement strategies for two large-scale future opportunities:
Infrastructure Provider: The IP will be responsible for taking forward the design, building, and financing the majority of assets within the project.
Main Works Contractor: To construct and commission under a target price contract, working initially with TW and then the IP.
An invitation to tender for the key roles on the project will be issued in October this year.
Mohit Farmah, head of procurement and supply chain at Thames Water, said: “We are excited to kick-start the year by getting the next stage of market engagement for our proposed reservoir underway.
“Contractors and investors have a crucial role to play in informing our approach and helping drive this vital project forward. We have been encouraged by the level of interest the market has shown to date.
“I encourage all interested parties to register their interest to engage with us and shape the future of this vital project, including our spring market engagement event on Monday 17 March”.
Firms need to register their interest in the market engagement by clicking here before 24 January.