United Utilities is procuring a design and integration partner for its "Only Rainwater into Windermere" programme, with the appointment estimated at £600 million excluding VAT over 13 years from 1 April 2027. Trade press reported in October 2026 that a formal tender notice was expected in early November.
The scale of the scheme
The company estimates the full programme at up to £3.7 billion. Feasibility work by Jacobs and Mott MacDonald narrowed more than 70 options to two preferred tunnel solutions. The partner appointment would run well beyond the current price control, which ends in March 2030.
Work already under way
The new scheme sits on top of a £200 million Windermere catchment programme of 15 projects. Langdale and Grasmere are complete, Ambleside's storm tanks are due by December 2027, and a storage tank near the Glebe is due in early 2030. In its August 2026 draft cost change decision, Ofwat included £93 million (2022/23 prices) for the Windermere gated scheme. The final decision is due in December 2026.
Why the partner role matters
Much of United Utilities' 2025–2030 capital work is already allocated. Seven construction delivery partners hold about £3 billion of projects, and 18 design and build partners share around £2.75 billion. The Windermere role is the largest new appointment in view. It is also one of the few routes into direct work for engineering design and programme management firms, rather than subcontracting.
Pressure on the company's wastewater performance adds weight. The Environment Agency counted 388 pollution incidents in 2025 and kept United Utilities at two stars.
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