Massive “fatbergs” are choking London’s sewers and causing untold problems, and according to a survey conducted by Thames Water, most of the many restaurants and takeaways in the capital are responsible.

Recently the issue of fatbergs hit the headlines when a 130-tonne fatberg, described as a “total monster” by Thames Water, was found under Whitechapel Road in east London. Thames Water found that not one of the restaurants on the road had a working grease trap.

While wet wipes are a major contributor to the ‘monster’ blockage discovered in London sewers, the survey found that 90% of the eateries in London are the major contributors to the problem because they are not installing grease traps. This results in grease, oil and food scraps washed off plates, utensils and saucepans are finding their way into pipes and drains.

The Whitechapel fatberg was longer than Tower Bridge at a whopping 250 metres in length, and weighed as much as 19 African elephants.

Stephen Pattenden, sewer network manager for Thames Water, said: “We’re not suggesting anyone intentionally pours the contents of a fat fryer down the drain, but it’s more about the gunk that comes from dirty plates, pots and pans. A simple, well-maintained grease trap will capture that stuff and stop it entering the sewer and turning into a monster fatberg.”

The fatberg has caused major damage to the Victorian sewer system, and teams of workers armed with high-powered jets and shovels have been toiling seven days a week to break up the blockage.

Had this massive fatberg not been discovered during a routine maintenance inspection last month, the congealed mass of fat, nappies and wet wipes could have ended in raw sewage flooding on to the streets of east London.

Thames Water said that despite the time and expense of clearing the Whitechapel fatberg, it will be converted into about 10,000 litres of biodiesel – enough to power 350 double-decker Routemaster buses for a day.

Tanker-loads of the “evil, gut-wrenching, rancid blob”, as Thames Water waste network manager Alex Saunders described it, have been taken to a specialist plant run by Argent Energy to be processed into the fuel, which burns more cleanly than regular diesel.

“Previously, we’ve either extracted the fatberg out of the pipes and sent it to landfill, or broken it down and put it back through the sewage treatment process. Even though they are our worst enemy, bringing fatbergs back to life when we do find them, in the form of biodiesel, is a far better solution for everyone” he added.

Pattenden said restaurants that failed to install grease traps and other measures faced prosecution if they didn’t make required changes.

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