World-first Fatberg Autopsy for Channel 4 reveals UK sewer secrets

Category: News Release

  • Fatberg Autopsy: Secrets of the Sewers airs tonight at 9pm on Channel 4, revealing the contents of a London fatberg
  • Cooking fat is biggest contributor to Britain’s fatberg crisis, making up nearly 90% of the fatberg sample
  • Testing discovered potentially lethal antibiotic-resistant superbugs
  • Testing showed wet wipes labelled as “flushable” which do not disintegrate in the sewers
  • Sample showed a higher concentration of prohibited gym supplements than street drugs like cocaine and MDMA


A pioneering one-off special for Channel 4 has revealed the filthy secrets contained within a supersized fatberg. Fatberg Autopsy: Secrets of the Sewers (Tonight at 9pm on Channel 4) will expose the contents and makeup of one monster blockage of congealed fat, wet wipes and human waste discovered underneath the streets of London.

Fatbergs are becoming a growing problem across the UK as our sewage infrastructure struggles to cope with Britain’s changing habits. The battle to remove them is costing an estimated £80 million a year across the UK, a bill that ultimately falls to utility customers in their water bills. In a world first, one supersized fatberg extracted from near the South Bank in central London has been forensically analysed in conjunction with Thames Water for a one-off Channel 4 special. The fatberg is thought to be larger than the infamous Whitechapel discovery, one of the largest ever found in Britain.

The programme sees presenter Rick Edwards and pathology technician Carla Valentine overseeing the process as the fatberg emerges from the sewers and makes its way to Abbey Mills Pumping Station in East London, dubbed “the cathedral of sewage”, for a thorough examination of its contents.

Typical items found in the fatberg included condoms, sanitary towels, nappies, wet wipes and cotton buds. But it’s the in-depth analysis by the specialist team of scientists which revealed new insights into a growing urban crisis.


Cooking oil is a key culprit

The fatberg sample was analysed to find what type of fats are contributing to blockages like this. A small quantity of fats come from personal hygiene and beauty products. Topically applied creams and gels which may contain oils and fats can make their way into the sewer from bathing and washing. However it’s fats and grease from cooking which make up the largest proportion of the fatberg. Just under 90% of the sample is comprised of palmitic acid, commonly found in cooking oil, and oleic acid found in olive oil.


Trivial name of parent fatty acid

Percentage content

Palmitic acid


Oleic acid (or Elaidic acid) (variant 1)


Oleic acid (or Elaidic acid) (variant 2)





Myristic acid


Erucic acid



Water companies continue to advise members of the public to not dispose of oils and fats down the sink, with Thames Water running a “bin it, don’t block it” campaign to discourage customers and commercial food outlets from throwing cooking fats down the drain.


The scourge of wet wipes

This fatberg, like many others found up and down the country, is extensively made up of wet wipes. Civil engineering consultant Andy Drinkwater from the WRc describes the formation: “the fat sticks to the side of the pipe, the wet wipes come down and stick on the fat, other fat comes down and sticks to the wet wipes and that adds to the mass of the fatberg”.

The concern with many wet wipes is that, unlike toilet paper, they aren’t designed for being flushed into the sewer. A series of tests took place at the autopsy to discover how a number of wipes and toilet papers respond in similar conditions of motion and submergence as in a sewer. The tests showed that while ordinary toilet paper breaks down some of the wet wipes, including some brands which have been labelled as “flushable”, are unable to disintegrate in these conditions. Wet wipes can contain the plastic polypropylene which gives the product extra strength for consumers, but consequently makes it unable to disintegrate if disposed of incorrectly.

Some wipes are described as “flushable” on packaging but once they reach the sewer do not break down. New guidelines recommend that any wipes marked ‘flushable’ must pass a series of tests to prove they break down in the sewer and any that don’t pass must have a ‘do not flush’ label on the front of the pack. However, there’s currently no regulation to force companies to comply.


Superbug discovery

The fatberg sample was tested for dangerous bacteria. The tests found potentially infectious bacteria including listeria, campylobacter and E.coli. The team also tested the sample to see if any bacteria would grow in an agar dish treated with antibiotics. The results discovered bacteria which were able to thrive in the antibiotic environment. Antibiotic resistant bacteria, sometimes known as ‘superbugs’, are a grave concern for public health. Bacteria like these pose an immediate risk to the operatives who work inside the sewers as any infection could prove life-threatening. The public at large could be at risk in the event of a sewer blockage, as contents of the sewers, including these harmful superbugs, could come back up through domestic or commercial pipes causing flooding to homes and businesses.

Thames Water waste networks manager Alex Saunders: “We and other water companies are facing a constant battle to keep the nation’s sewers free from fatbergs and other blockages. For the sake of our sewer workers like Vince and the other guys who feature in the show please only flush the three Ps (pee, poo and toilet paper) and don’t feed the fatberg.”


Drugs secret

The fatberg autopsy also uncovered evidence indicating people’s contact with street drugs and other pharmaceuticals.

The team breaking up the fatberg to examine its contents discovered in-tact drugs-related items, including small plastic ‘baggies’, a needle and syringe. Presenter Rick Edwards describes the finds as “a sobering window into the lives of people living above the sewer”.

The forensic analysis of the sample also found chemical traces of a cocktail of drugs. Dr John Wilkinson from the University of York collaborated with a team from Cambridge using mass spectrometry to identify different chemicals inside the fatberg. The teams analysed the sample for traces of pharmaceutical chemicals and discovered a high proportion of salicylic acid, commonly found in topical creams for acne, and paracetamol. The tests also discovered evidence of hordenine and ostarine, both of which can be found in performance enhancing sports supplements. Ostarine, which is used for muscle gain, is on the World Anti-Doping Agency’s prohibited list and is not licenced for medical use in the UK. Hordenine and ostarine represented over half the proportion of pharmaceuticals found in the tested sample.