An £18m upgrade of historic sewers aimed at reducing the risk of flooding has been completed.

Southern Water says it had to call in mining experts during the project in Thanet as some tunnels were so deep.

The work, which started in May 2022, was carried out across Margate, Birchington, Westbrook, and Cliftonville.

Bosses say the scheme included relining and sealing pipes internally using the latest technology as some of the tunnels were more than 100 years old.

Southern Water surveyed 500 manhole covers, replacing many of them, while internally relining 218 sewers, and excavating and repairing 38 of those.

Gus Winterbottom, company project manager, said: “We’ve used mining experts to access ageing chalk tunnels because they are so deep underground.

“We have also accessed the tunnels through manholes and used state-of-the-art CCTV surveys.

“The project surveyed and fixed the sewer network across and this work will help prevent flooding and help the environment.

“We kept residents updated at all times of the work, sending about 65,000 customer letters to households and businesses across 761 locations in Thanet.”

Southern Water says it remapped 70 miles of sewers with CCTV, which allowed engineers to focus in on the 12 miles where work was needed most.

Sewer sealing involves inserting a specially manufactured high-strength sock into an existing pipe.

It is then inflated and cured in place with UV light, creating a strong, seamless lining.