Huge reservoir wall installed in 72-hour operation

A major engineering milestone has been reached on what is set to become the UK's first new reservoir in over three decades.

Portsmouth Water said teams at Havant Thicket Reservoir installed a 20‑tonne steel cut‑off wall during a continuous 72‑hour operation at the start of the year.

The structure will sit beneath the reservoir's main embankment, forming part of work to create a new water source designed to protect rare chalk streams in Hampshire.

Once completed, the reservoir will hold about 8.7 billion litres of water and provide supplies across the south of England.

The steel wall, which is 13m (43ft) high and 9m (29ft) wide, was built on site before being lifted into a deep trench using a 100‑tonne crane.

Engineers lowered it into position with a margin of precision of just 25mm.

Because the trench was filled with a fast‑hardening waterproof mixture, teams worked in rotating shifts around the clock to complete the task safely within the three‑day window.

Bob Taylor, chief executive officer of Portsmouth Water, said it was a "major milestone" for the project.

He said: "Working continuously for 72 hours presented challenges and we were acutely aware of the need to keep disruption to a minimum for local residents.

"We made sure noise and lighting were reduced as far as possible and installed an acoustic barrier, to ensure as little noise as possible travelled from site.

"I would like to thank everyone for their patience and understanding while this key piece of work took place."

The reservoir is expected to be completed by 2031.