Britain’s New Reservoir Programme: Delays, Demand and Alternatives

In 2025 the UK government pledged to construct nine new reservoirs across England to increase water storage capacity. The sites are slated for Lincolnshire, Cambridgeshire, Oxfordshire, Somerset, Suffolk, Kent, East Sussex and the West Midlands. The most advanced projects are the White Horse reservoir near Abingdon (planned completion 2040) and the Fens reservoir near Cambridge (planned completion 2036). A separate reservoir, Havant Thicket near Portsmouth, which began before the 2025 pledge, is expected to open in 2031 and will be the first major new reservoir in England in more than three decades.

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Building a reservoir typically requires 15–25 years from proposal to operation. Locating a suitable site is the first hurdle; reservoirs need several square kilometres of land and appropriate soil for embankments, and such sites “don’t grow on trees”. Planning permission adds further delay, with local councils often under-resourced. To accelerate the three most advanced schemes, the government has designated them as “nationally significant infrastructure”, moving final planning decisions to the national level, but the remaining six lack this status.

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Geography also complicates construction. The South and East of England, where water demand is highest, are largely flat and lack valleys suitable for traditional damming. Instead, artificial lakes must be created with ring embankments of specialist clay, a costlier approach. Filling the reservoirs is challenging because many sites lack a single large river and must rely on pumping water from smaller sources during winter, a factor that stalled the Fens reservoir’s planning progress.

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The Environment Agency estimates England will need an additional five billion litres of water per day by 2055, far exceeding the roughly 700 million litres the nine new reservoirs are expected to supply. Professor Hannah Cloke of the University of Reading notes that the UK water network does not store years of water, so a single wet winter cannot guarantee supply through a dry year. Dr Megan Klaar of the University of Leeds warns that Labour’s pledge to build 1.5 million new homes before the 2029 general election will intensify demand, especially in regions already facing hose-pipe bans.

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Experts argue that reservoirs alone will not secure future water supplies. Dr Kevin Grecksch of the University of Oxford highlights water reuse—treating wastewater for irrigation or drinking—as a “hot topic” with existing technology, citing successful adoption in several EU countries. He is less enthusiastic about desalination, describing it as energy-intensive, producing toxic brine, and costing roughly ten times more than treating river or reservoir water. Both Klaar and Cloke stress demand-side measures: mandatory water-saving devices in new homes, rain-water collection systems, and water metering to encourage conservation. Cloke also emphasizes fixing leaks, which currently waste 2.9 billion litres daily.

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The Department for Environment, Food and Rural Affairs has committed £104 billion of private investment to address leaks, construct the nine reservoirs and secure supplies, and is fast-tracking projects designated as nationally significant. The White Horse and Fens reservoirs remain in planning and design, with target completions in 2040 and 2036 respectively. Havant Thicket is on track for 2031. Continued progress will depend on resolving site-filling plans, streamlining planning approvals and integrating broader water-management strategies.

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