Winters in the UK are now 12% wetter than in 1960, with six of the ten wettest years on record since 1998, according to Met Office data.

With researchers expecting very heavy downpours to become more frequent, towns and cities are upgrading infrastructure to cope.

In St Helens, the town centre regeneration and construction of a state-of-the-art Transport Interchange include underground flood attenuation tanks to relieve pressure on local drains and reduce the risk of flooding.

The attenuation systems have been installed during the current programme of slab foundation works by main contractor VINCI Building, acting for St Helens Borough Council and ECF, a partnership of Homes England, Muse and L&G.

Attenuation tanks collect runoff from roofs, paved areas and other impermeable surfaces through pipes and inlets, temporarily storing the water before a flow-control device releases it back into the drainage network at a manageable rate to cut peak flows during heavy rain.

As urban areas expand and impermeable surfaces increase, engineered local solutions like attenuation tanks become more important. National policy, including the Flood and Water Management Act 2010 and the National Planning Policy Framework, has increasingly prioritised such measures.

Martin Horton, Senior Project Manager at VINCI Building, said: "Attenuation systems have an important role to play in reducing the risk of flooding and future-proofing urban environments. They also offer significant environmental benefits to St Helens, such as improving water quality by filtering out pollutants.

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"When installed underground, they are much more cost-effective and space-efficient than expanding traditional drainage infrastructure. By releasing rainwater steadily over time, they reduce the strain on drains, minimise wear and tear, extend the lifespan of existing infrastructure, and reduce maintenance costs."

The St Helens tank has a capacity of about 300,000 litres, helping to ease pressure on neighbourhoods near the bus station. Its top sits roughly a metre below the road surface.

Councillor Richard McCauley, Cabinet Member for Regeneration at St Helens Borough Council, said: "This is a once-in-a-lifetime regeneration project, and we have to consider measures that help the town now but will also be valuable for future generations. The UK is experiencing more frequent and intense rainfall events, which overwhelm traditional, often aging, drainage and sewer systems. The system we have installed for St Helens will store excess water temporarily and release it at a controlled rate, protecting the town centre from flooding."

Matt Whiteley, Senior Development Manager for ECF, commented: "The project team is delivering some complex engineering to ensure St Helens town centre has robust infrastructure. Attenuation tanks are a crucial tool in making towns and cities more resilient to flooding and the pressures of urban development in a changing climate. We're pleased with the progress, and this is another important milestone completed."

Cllr Steve Foulkes, chair of the Transport Committee at the Liverpool City Region Combined Authority said: "The installation of these rainfall attenuation systems is a prime example of how thoughtful, resilient design is being integrated into the build of this key piece of transport infrastructure for the region. They're yet another crucial element of the project to deliver a new interchange in St Helens town centre, which will better connect local communities with opportunity and each other."

The Met Office's latest State of the UK Climate report shows 2011–2020 was 9% wetter than 1961–1990, with more days exceeding the 95% and 99% historical rainfall thresholds and an increase in events over 50mm, indicating more frequent and intense rainfall.

Once completed, the St Helens Transport Interchange will improve journeys for bus passengers, cyclists and pedestrians, offering a safe, accessible and welcoming gateway to the town centre.

Key features include 11 bus stands (up from nine) to support the region’s bus franchising plans, temperature-controlled concourses, real-time information for buses and trains, step-free access throughout, and automatic doors at every stand. A Travel Centre, accessible toilets including a Changing Places facility, and secure indoor and outdoor cycle parking with improved wayfinding are also planned.

The surrounding public realm will be upgraded to strengthen links between the Interchange, St Helens Central rail station and landmarks such as the Gamble Building, Theatre Royal and the forthcoming Hampton by Hilton hotel. A new civic square, improved lighting and high-quality landscaping will create a more people-friendly public space.