A joint venture between Arup and Binnies has been appointed by Southern Water to lead the planning phase of a major water-transfer scheme linking the proposed Abingdon reservoir in Oxfordshire to Hampshire.

The Thames to Southern Transfer (T2ST) project would involve construction of an approximately 80km strategic pipeline capable of moving up to 120Ml of water a day from the proposed White Horse Reservoir in Oxfordshire into Hampshire.

The T2ST is intended to reduce abstraction from local rivers, including vulnerable chalk stream systems, and support water supply in a region of the UK that faces chronic stress on water resources. It forms part of the Strategic Resource Options (SROs) programme, a large collection of schemes coordinated across the water sector to improve resilience. The SROs programme is currently estimated to involve around £104bn of investment.

As technical partner, the Arup–Binnies JV will lead planning, design and environmental assessment for the pipeline, carry out ground investigations and assess constructability. The team will also work towards securing development consent and supporting procurement for the main construction contractor.

The appointment builds on the joint venture’s ongoing involvement in developing the White Horse Reservoir, previously referred to in planning documents as the South East Strategic Reservoir Option (Sesro), which is being taken forward by Thames Water with support from Southern Water and Affinity Water.

Last week, Thames Water fired the starting gun on the “extensive” process for appointing a main contractor to design, build, test and commission its major new Oxfordshire reservoir in a deal worth £5.7bn.

Southern Water said projects such as the reservoir and interconnector pipe are intended to provide longer-term resilience for the South East, reducing pressure on rivers and helping companies manage supply during droughts and as climate change alters rainfall patterns. The pipeline would enable water captured and stored in Oxfordshire to be moved to areas with greater shortfalls.

Environmental groups have repeatedly warned that large water infrastructure projects can carry risks for habitats and local communities, and that conservation of chalk streams and river ecosystems requires careful, evidence-led reduction in abstraction.

Local authorities and regulators will scrutinise the proposal’s environmental assessments and mitigation plans as it proceeds through the consenting process.

Arup-Binnies JV’s remit is to complete the planning and design steps needed to secure development consent and support procurement.

Delivery time will be a critical issue for the sector, which faces pressure to bring new capacity online to maintain reliable supplies while meeting regulatory and environmental obligations.

The appointment marks a step towards developing a network of strategic options that water companies and regulators say are necessary to secure supplies across south-east England, but the project must still satisfy planning, environmental and funding tests before work can begin on the ground.

Arup Binnies joint venture framework director Tim O’Brien said: “Building on the success of our Arup Binnies joint venture delivering the White Horse Reservoir, we are proud to extend this partnership to the Thames to Southern Transfer project.

“Delivering resilient water supplies for the future depends on strong collaboration and, together with Southern Water, we are committed to driving innovation and sustainability to secure water resources for generations to come.

“Drawing on our expertise across the UK and the globe, it underscores our commitment to delivering innovative, resilient, and future-proof infrastructure.”

Arup integrated major projects leader Mark Job said: “This project is a major step in strengthening the UK’s water resilience in a highly stressed region. Our partnership approach for the White Horse Reservoir reflects a new model for delivering major infrastructure – one built on collaboration and shared responsibility for the outcomes.”

Southern Water major projects director Ben Ring said: “The Thames to Southern Transfer is one of a number of new water sources we’re developing for our customers in Hampshire which, together with our investment in the White Horse Reservoir, will reduce the amount taken from the county’s rare and sensitive chalk streams.

“It’s great to have Arup and Binnies on board to help us deliver the planning phase of this essential project.”

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