White Horse Reservoir £5.7bn tender: delivery model and design lens for engineers
Reviewed by Joe Ashwell
First reported on The Construction Index
30 Second Briefing
Thames Water has opened a £5.7bn tender for the White Horse Reservoir near Abingdon, a 150‑billion‑litre strategic storage scheme intended to supply Oxfordshire, Wiltshire, Hampshire and London and deliver up to 120 million litres per day to Southern Water during drought via the planned Thames to Southern Transfer pipeline. Procured under the Specified Infrastructure Project Regulations, the main works contractor and separate infrastructure provider will follow the Thames Tideway Tunnel model, with a new Ofwat‑licensed entity financing and delivering the asset. Requests to participate are due by 24 April 2026, with water deployment targeted from 2040 and around 1,800 construction jobs forecast.
Technical Brief
- Procurement is split into separate main works contractor (MWC) and infrastructure provider (IP) contracts under SIPR.
- Thames Water will submit a Development Consent Order application later this year for planning approval.
- A new Ofwat‑licensed regulated entity (the IP) will finance, own and deliver the reservoir asset.
- Thames Water leads development in partnership with Affinity Water and Southern Water as co‑beneficiaries.
- MWC scope covers design, build, testing and commissioning of the full reservoir system.
- Online applicant briefing for prospective MWCs is scheduled for 11 February 2026, with registration closing 10 February.
- Requests to participate must be lodged by 24 April 2026 via notice 005547-2026.
Our Take
Within our 522 Infrastructure stories, very few UK water pieces involve single-project tenders on the multibillion-pound scale, signalling that White Horse Reservoir is likely to sit alongside Thames Tideway as one of the key long-cycle civils packages in the UK pipeline to 2040.
The 150-billion-litre storage and 120-MLD drought yield, combined with the Thames to Southern Transfer pipeline, indicate that Thames Water is planning an integrated regional system rather than a standalone asset, which will complicate interface risk and programme management for contractors bidding the £5.7bn package.
Given Ofwat’s presence in the article facts and the 2040 water-available date, bidders should expect regulatory scrutiny on cost efficiency and resilience outcomes over multiple price-review periods, affecting how risk, inflation and performance incentives are structured in JV and supply-chain arrangements.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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