A massive fatberg weighing the same as 11 double decker buses is blocking a sewer in east London.
The 250 metre long solid mass was found in Whitechapel and is made up of wet wipes, nappies, fat and oil.
Thames Water say it is blocking a stretch of sewer more than twice the length of two Wembley football pitches.
The fatberg is around 10 times bigger than the famous Kingston monster found in 2013.
Work on Whitechapel Road to remove the fatberg started this week and involves an eight-strong crew using high-powered jet hoses to break up the mass before sucking it out with tankers.
The operation will take three weeks to complete.
Thames Water's head of waste networks Matt Rimmer said: "This fatberg is up there with the biggest we’ve ever seen.
"It’s a total monster and taking a lot of manpower and machinery to remove as it’s set hard.
"It’s basically like trying to break up concrete. It’s frustrating as these situations are totally avoidable and caused by fat, oil and grease being washed down sinks and wipes flushed down the loo."
Mr Rimmer added: "We check our sewers routinely but these things can build up really quickly and cause big problems with flooding, as the waste gets blocked.
"It’s fortunate in this case that we’ve only had to close off a few parking bays to get to the sewer.
"Often we have to shut roads entirely, which can cause widespread disruption – especially in London."