Record ‘concreteberg’ discovered in London sewer

A record-breaking “concreteberg” as heavy as a blue whale has appeared in a London sewer.

The blockage, 100 metres long and weighing 105 tonnes, is the largest that Thames Water has ever seen. The firm blamed workmen pouring concrete down drains for it.

It said it believed it will take at least two months to remove with specialist equipment including pneumatic drills and high-pressure jets, at a cost of several hundred thousand pounds or more.

The solidified concrete, found during a routine check under Hall Street in Islington, is denser than a “fatberg” of fat, oil and wet wipes, and has set to the walls of the Victorian-era sewer.

“This is not the first time damage has been caused by people pouring concrete into our sewers but it’s certainly the worst we’ve seen," said Alex Saunders, Thames Water operations manager. “It’s very frustrating and takes a great amount of time and effort to resolve.

“We’re now doing everything we can to deal with it as quickly as possible, making sure our customers don’t have to suffer because of this mindless abuse of our network.”

When work begins next week, tankers will be on standby to pump out any backed-up sewage blocked by the concrete, Thames Water said.

Blockages cost the company around £18m each year.

It tweeted: “It goes without saying that pouring concrete down the drains into our sewers isn’t going to do any good.”