A major £42 million flood scheme has officially opened, providing better protection from flooding for homes, businesses and essential services in Tonbridge and Hildenborough.

Photo: New Leigh flood barrier

The expanded Leigh flood storage area and new Hildenborough embankment scheme will reduce flood risk to 1,870 homes and 575 businesses, while also benefiting communities further downstream along the River Medway.

The scheme has increased the capacity of the Leigh flood storage area by around 23 per cent. By raising the maximum stored water level at the control structure by 55 centimetres, the expanded storage area can now hold approximately 7.4 million cubic metres of floodwater, equivalent to around 2,880 Olympic-sized swimming pools.

The scheme will help communities respond to the growing challenge posed by climate change, with increased likelihood of more frequent, severe storms and extremely wet winters. The project has also improved the reliability and resilience of the structure, enabling it to continue reducing flood-risk for the next 50 years.

The original Leigh flood storage area was completed in 1982, and has since played a vital role in protecting downstream communities and was operated 75 times between 1981 and summer 2026 to reduce flood-risk.

Simon Curd, flood-risk manager for the Environment Agency in Kent, said:

“This is a major investment in the safety and resilience of communities along the River Medway. The original Leigh flood storage area has protected Tonbridge and Hildenborough for more than 40 years, but climate change means we must be prepared for more severe storms and wetter winters.

“By increasing the amount of floodwater the area can store by around 23 per cent and improving the reliability of its gates and operating systems, we have made sure this vital structure can continue reducing flood-risk for the next 50 years.

“This was a highly complex engineering project, delivered while the flood storage area remained operational. I would like to thank our partners, contractors, landowners and local communities for helping us complete it successfully.”

Photo: New gate at the Leigh Barrier

Major engineering work at Leigh

The project team completed the work over 3 years while ensuring the flood storage area remained fully operational, protecting downstream communities.

New 12.5 tonne gates were installed. Each one was manufactured off-site in sections before being welded together on site and lifted into place with a 300 tonne crane. New lifting and electrical systems were put in place, and moving platforms built to ensure the structure could be maintained more easily.

New protection for Hildenborough

The expanded storage area works alongside new defences in Hildenborough, where a significant source of flood risk is the River Medway backing up into the Hawden Stream.

The Hildenborough scheme includes a 98-metre embankment across the floodplain, a new pumping station on the Hawden Stream, and a sheet-piled wall. Together, these measures prevent water from the River Medway backing up into Hildenborough without increasing flood risk elsewhere.

Approximately 180 Hildenborough homes affected by flooding in 2013, along with many others, will benefit directly from the new embankment and pumping station. Other properties will benefit from the additional capacity provided at Leigh.

The Leigh flood storage area sits between Leigh and Penshurst on the River Medway. It consists of a 1.3-kilometre-long, 5-metre-high earth embankment and a control structure containing 3 steel gates.

During normal river conditions, water passes through the control structure. When flooding is forecast, the gates can be used to limit the flow and temporarily store water upstream, reducing peak river levels in downstream communities.

A trained Environment Agency operator is available 24 hours a day, 365 days a year to monitor catchment conditions and weather forecasts and operate the structure when properties are at risk.

The flood storage area is part of a wider flood-risk management system that includes the Tonbridge town walls and the natural floodplain at the sports pitches.

The scheme cost approximately £42 million to design and construct and will provide more than £155 million of benefits to downstream communities.

Funding  for the scheme comprised:

• £36,616,500 of Flood Defence Grant in Aid;
• £2,500,000 from Kent County Council;
• £2,298,500 from the South East Local Enterprise Partnership;
• £500,000 from Tonbridge and Malling Borough Council; and
• £85,000 in levy funding.

The project was delivered through partnership working involving the Environment Agency, Tonbridge and Malling Borough Council, Kent County Council and the Kent and Medway Economic Partnership.

The Environment Agency’s national flood-risk assessment - NaFRA2 - published in 2024, shows that around 6.3 million homes and businesses in England are in areas at risk of flooding from one or a combination of sources: rivers, the sea, and surface water.

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