Thames Water Utilities Limited has published a tender notice for the Main Works Contract for White Horse Reservoir (formerly SESRO). The notice sets out a procurement for a multi supplier framework agreement plus an associated single call off contract, using a competitive flexible procedure under the utilities regime.
This is a significant programme, with the notice stating an estimated total value of £5.7bn (ex VAT) and contract dates running well into the 2040s.
Key dates at a glance
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Online applicant briefing: 11 February 2026 (register by 10 February 2026 at 12 noon)
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Enquiry deadline: 7 April 2026, 11:00am
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Deadline for requests to participate: 24 April 2026, 11:00am
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Estimated contract dates: 11 August 2027 to 31 March 2043
What is being procured?
This tender notice relates to the Main Works Contract only, comprising:
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a bespoke multi supplier framework agreement, and
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a single call off contract delivered via a two stage early contractor involvement approach (Stage One planning and design development, then Stage Two detailed design and build).
The call off is intended to be based on NEC4 Engineering and Construction Contract (Option C) and references X22 (ECI) in the description.
What to focus on at the request to participate stage
At this stage, bidders are typically assessed heavily on:
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relevant programme experience (major civils, tunnelling, water infrastructure, complex consents)
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financial capacity and delivery assurance
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governance, risk and controls that stand up across a long delivery horizon
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delivery model, including integration of supply chain and specialist subcontractors
The notice indicates an intention to shortlist up to four suppliers to invite to tender.
Practical preparation steps to take now
This is not a “wait for the ITT” opportunity. If you are interested, you will likely need:
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a mapped evidence set: comparable projects, scale, complexity, stakeholders
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named delivery leadership and governance (programme controls, commercial, quality, H&S)
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a credible supply chain model that matches the scope (civils, tunnelling, M&E, environment, logistics)
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early thinking on target price approach and what you will need from the client to de-risk Stage Two
If you want an external review of your procurement strategy or submission approach, our procurement consultancy services and bid writing support can help you decide where to focus effort and how to present the strongest evidence early.
