Nobody remembers exactly who coined the word, but it started off as a bit of slang used by the Thames Water “flushers” who work to keep the sewers flowing freely beneath London. Their word first surfaced from those Victorian tunnels and into the newspapers in August 2013, when a bus-sized “fatberg” – a solid mass of oil and grease and undisposable disposables – was removed from a sewer in Kingston upon Thames. After that the name caught on in the way that its rival “johnnyberg” (used by the flushers of Anglian Water, who had been struck by the preponderance of condoms in the ossified deposits) did not. “Fatberg” reached the Oxford English Dictionary in 2015 – at the same moment as “manspreading” and “Brexit” and “bantz” – and in the same year in which a record-breaking 10-tonne example broke a sewer in Chelsea costing Thames Water £400,000 to fix. But it wasn’t really until last year that “fatberg” went viral.

The Whitechapel fatberg that made headlines in September was among our most infectious social media exports of 2017. The units in which it was routinely measured gave away its birthplace. This being a London phenomenon it was invariably described in local currency: at 820 feet, the fatberg was “longer than Tower Bridge” or “twice as long as Wembley Stadium” and “the weight of 11 double-decker buses”. Having once led the world in sewer engineering with Sir Joseph Bazalgette’s cavernous underground network of marvellous tunnels, London was now the undisputed global leader in sewer blockage. TV crews were dispatched from Moscow and Montreal and Madrid to stand above manhole covers along Whitechapel Road and hold their noses while Thames Water flushers in white protective suits used high-powered jet hoses and picks and shovels and vacuum pipes to break the fatberg up and then remove it in tankers at the rate of 20 to 30 tonnes per day. Ninety three per cent of its complex structure was said to consist of the element “wet wipe”. By the time the clean-up was over, and its notoriety had spread, lesser fatbergs were being unearthed in Belfast and Denver and Melbourne.

It was in the first week of the discovery of the Whitechapel Monster (the hyperbole was part of the attraction, no nomenclature for the Subterranean Beast was too extreme) that the Museum of London, halfway through a series of exhibitions about modern city living, decided it must have a slice of it. Sharon Ament, the museum’s director had been thinking about the possibility of displaying a fatberg in the museum – whose collection includes a variety of valuable objects retrieved from drains and cess pits and sewers from Roman times on – since the previous big find in Chinatown in Soho. On that occasion the museum had not acted before the fatberg was destroyed; this time it was ready. (Apparently there was some talk that the Science Museum wanted a chunk of fatberg too, though when it discovered the Museum of London had first dibs there was, by some accounts, a collective sigh of relief among the curators there.)

At the end of this week, a representative chunk of the Whitechapel Leviathan will be put on display at the Museum of London. It is likely that no lavatorial exhibit will have caused quite as much a splash since Marcel Duchamp invented conceptual art with his urinal a century ago.

The woman charged with curating Fatberg! is Vyki Sparkes, who looks after social and working history at the museum. “It was like the finger of fate pointed at me,” she explains to me in the museum’s cafe, with well-scrubbed hands and a slightly rueful smile. She is unsure yet on how high up her CV “curator of 21st-century sewage” will appear, but she is confident that the exhibition will be a worthy addition to the museum. “If you went up to someone in the street and asked them to talk about what they put down their toilet they would tell you to bog off, basically,” she says. “But this is a way to open that conversation. We are not here to tell people how to behave, I am here to reflect how we live and to raise questions.”

Those questions are welcomed above all by Thames Water, some of whose employees have begun to feel fatbergs looming over every part of their life, crowding in on them. Alex Saunders has been working on waste networks for four of his six years with the company, but on the Whitechapel Fatberg, and its ripple effects, for most of the past four months. The East End Mammoth was, he suggests to me, “kind of a perfect fatberg storm”. A fatberg needs two principal elements to evolve. The first is a large and regular amount of oil and grease poured into sewers; the second is a population that flushes wet wipes and tampons and condoms and nappies down the toilet.

If you go and stand in Whitechapel Road, Saunders suggests, you could guess it was likely fatberg territory. It is a street lined with cafes and restaurants and takeaway outlets. Then there is the Royal London hospital, “which can lead to the flushing of some sanitary products”, and also a very high density of flats and houses.

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When you walk along that stretch of road it seems extraordinary that the fatberg could evolve to such a scale beneath your feet without Thames Water noticing it – or without the sewers backing up and flooding. Part of the reason for that is the sheer volume of the London network, Saunders suggests. The pipework is “hundreds of thousands of kilometres long” and “you cannot be sticking your head down the same bit of sewer every week”. The Whitechapel sewer, part of Bazalgette’s original brick-built labyrinth, has an inverted egg-shape cross-section; the bottom is narrower than the top so during a time of low flow there is a thin channel to keep it moving and when it rains the sewer amplifies. The fatberg had formed along the upper part of the tunnel. Below it there was still a good flow and therefore no warning signs. “Then suddenly,” Saunders recalls, “during our normal inspections the guys popped down there and found this thing that turned out to be bigger than Tower Bridge.”

The Whitechapel Behemoth had hardened into a kind of concrete. The flusher teams have a variety of high-pressure jets, some revolving, some with chains and drill bits, to break up the bergs, which they try to use like keyhole surgery, careful not to damage the sewer itself. “We have lots of weapons at our disposal,” Saunders says, “but sometimes, as with the Whitechapel one, it is so impacted that a lot of it is the teams going down and chiselling away by hand.”

In London, which has a magnified version of a universal problem because the sewers are so large, this work never stops. Thames Water has teams working full time; usually they are aware of five or six fatbergs that are growing. Some cause immediate blockages, others like the one in Whitechapel don’t. Saunders estimates the work costs £1m a month, but that doesn’t include the collateral damage of “sewage flooding living rooms and public spaces cordoned off and out of bounds because they are contaminated”.

In many cases the job of flusher in London is a family occupation, the work traditionally passed down from father to son, much like the job of undertaker. Saunders was out with some second- and third-generation sewer flushers, the other evening, men who have been doing the job for 30 years themselves. In the past, they suggested, there was a good deal of job satisfaction in the work; it had a nice psychological trajectory: they started a shift with a blockage, and ended it with the sewer flowing freely. It is only in the last few years that they have found themselves routinely hacking away at fatbergs.

When the Museum of London decided to take a chunk of the material the flushers raised an eyebrow, Sparkes recalls. The idea is that the world below street level does not invade the world above. The size of the sample was inevitably limited by what could come up through a manhole. The museum ended up with two sizeable chunks. To give a sense of its original serpentine scale they thought about installing it in a case with Victorian infinity mirrors which would extend it as far as the eye could see, but that idea was eventually abandoned.

Because the substance itself is somewhat volatile though, and of an unusual consistency, they still had to rewrite procedure to work out how to deal with it. “We had our head of conservation look at it,” Sparkes says. “We initially thought about pickling it like one of Damien Hirst’s cows. The problem with that, we felt, was that it would likely make it liquid and runny.” What they did instead was to dry the samples. They did this at different rates, uncertain how it would respond. In the event, the one that was dried most quickly has crumbled into pieces; the other remains intact.

Health and safety was an inevitable concern. “Worst case scenario if it is handled incorrectly is death,” Sparkes suggests. “It has come out of the sewer so it might contain Weil’s disease.” There was a fear it might also hide disposed needles – another hazard of the modern sewer – so it was x-rayed with that in mind. Museum staff still approach the fatberg with extreme caution, in full body protective suits and masks and disposable gloves, disinfecting as if they are in an operating room. The fatberg remains in quarantine ready to be encapsulated in a specially sealed case. “One of the problems is you get all sorts of things that live inside it,” Sparkes says. “One of our samples unexpectedly hatched loads of flies in store.”

As well as breeding maggots, the fatberg breeds metaphors. It is hard not to think of it as a tangible symbol of the way we live now, the ultimate product of our disposable, out of sight, out of mind culture.

One of the reasons this feels like a distinctly London story, is the horrible history of the city and its effluent, a history that until recently seemed happily confined to the past. Prior to autumn 2016, the last time we looked so hard at sewage was during the Great Stink of 1858, when a combination of a hot and dry summer and the practice of discharging the raw sewage of a fast-growing population directly into the Thames, turned the river brown and saw sewage 10ft-deep at the river’s margins. MPs were forced to debate in Parliament with handkerchiefs over their faces. Cholera and typhoid were epidemic. Like the burghers of Hamelin menaced by rats, the government charged the director of metropolitan works, Joseph Bazalgette, with solving the problem. With 318 million bricks and over the course of 16 years he did just that.

Facebook Twitter Pinterest Another view of the Whitechapel fatberg. A third of Londoners admitted in a survey last year they had no idea you weren’t supposed to flush fat down the sink. Photograph: Thames Water

The Observer reported on Bazalgette’s grand plan on 15 April, 1861, suggesting it was “the most extensive and wonderful work of modern times”. The paper noted how the network would carry waste to a cathedral-like treatment plant beyond the city margins, from where “the united sewage of three areas will be conveyed to Mucking Flats in that reach of the Thames called ‘The Lower Hope’.” It also bemoaned the fact that “the inhabitants of this metropolis seem to take little interest in the great undertaking”.

It was the genius of Bazalgette to create a system designed to allow for enormous population explosion. His great underground caverns and diverted rivers, were designed to flow as 98% water. From the beginning, some of the city’s residents took advantage of the network as a rubbish disposal system, but it is only in recent years that the throwaway society has routinely clogged the network.

Flushers report finds of motorbikes, prams, coins, phones and jewellery – and once a live hand grenade. The toxic nature of some of the industrial waste that finds its way into the sewers means that fewer animals survive than in the past; rats are in decline; beyond that there are occasional terrapins and the odd gasping goldfish. A decade ago the biggest problem facing Thames Water was cotton buds which blocked the mesh of sieving drums at treatment plants. It is only since the advent of the wet wipe that the blockages have consistently advanced upstream.

Patented moistened close weave wipes first found a mass market at Kentucky Fried Chicken franchises in 1963 to obviate the need for so much finger lickin’. Moistened baby wipes became available in the 1990s, but it wasn’t really until Kimberly-Clark and Proctor and Gamble started marketing adult wipes as an alternative to loo roll in 2005 that sewage systems started to clog.

The global sale of moistened wipes is now a $17.5bn (£12.4bn) business, growing globally at around 4% per year. Many “adult” wipes carry the tag “flushable”, a description which means that they will likely get around the U-bend, but not that they will biodegrade in the sewer. “There is not a single wet wipe on sale that has passed the UK standard,” Saunders says. “The companies are marking their own homework when they say they are flushable.” Wipes are particularly resistant to degrading in water, and when after many years they eventually do, their plastic content becomes part of the problem you winced at on Blue Planet II.

Thames Water did some research last year with a sample of 2,000 people. A third said they put their wipes in the bin and never put fat down the sink. A third said they used to flush wipes down the loo and pour fat down the plughole but had changed their habits now after understanding the issues. And a third admitted they had no idea that you weren’t supposed to use the drains as a catch-all waste disposal. Thames Water tries to aim its education about the issue at fatberg hotspot areas, which has resulted in 20% fewer blockages.

The other part of the great fatberg equation has been the rise and rise of fatty and fast food as part of our diets. In 1884, Nathaniel Whiting of San Francisco patented the first grease trap to catch “substances which would tend to choke and clog the sewers”. His design is still the simple standard model for commercial kitchens: wastewater drains into a box where fat settles out. The problem is that eventually, someone has to clean the box out and dispose of the fat according to guidelines. Increasingly, it appears, this is a practice easily sidestepped and a regulation often ignored. Saunders suggests a simple solution: “I think as well as giving those health ratings on the doors of cafes they need to be inspected for their waste management. If they couldn’t get more than a ‘one out of five’ rating if they had no fat trap under their sink, we could change a lot of this overnight.”

With the Whitechapel Colossus, Thames Water tried to show an example of best practice. The tankers of fat and grease were filtered of sanitary products and refined into enough biofuel to power a London bus for a year. But that was an expensive one-off; a better plan is to have a system for recovering the fat before it goes into the sewage. The company is exploring the economics of a collection service. With Bazalgette-style organisation there is much potential. In the United States, there have been stories of gangs blowtorching their way into grease traps to steal used cooking oil that can be made into biofuels.

In the meantime, Saunders still exists in a world of fatbergs. Having had a great deal of experience with the substance how would he describe it?

He had a big lump in his gloved hands from Whitechapel. “It is browny, yellowy, greeny in colour, a bit slippery to hold but also very heavy and very hard, and when you cut into it you find a stitching of wet wipes holding it together.” He was with a team extracting a big lump the other week; it was like exhibit A: “there was a condom hanging out one side, a wet wipe the other, big globs of fat holding it together.”

Facebook Twitter Pinterest A fat-clogged London drain pipe.

At the Museum of London, the curatorial challenge has centred on the question of whether the fatberg was more like a soap or more like a candle. On balance, they have decided it is more like a candle. The sample that broke up has been sent to experts at Cranfield University to run a “fatberg autopsy” to discover exactly what it is made of.

Having worked with it for a few months, has Sparkes lost any of her sense of disgust?

She suggests it has become one of those uncanny objects where it is not immediately apparent whether it is animal, vegetable or mineral. Somewhere between compost and coral and bin juice. “It is really hard to classify,” she says. “Bits of it were wet to start with, now it is more like a crust. It is going slightly mouldy. There is a risk it will deteriorate on display.” The only distinctly synthetic thing you can quickly identify on its surface is, fittingly, the tiny purple and orange of a Double Decker chocolate wrapper. When they first received it, it was hard to get the smell out of your nose. “It has calmed down a bit now,” Sparkes suggests. “It is like a damp basement smell now, like someone has lived in a house for 70 years and done nothing to it.”

Though it clearly has some historical value, she views it very much as a one-off. “For us Whitechapel was the key moment in this story. We are not in the market every time there is a blocked pipe.”

Why does she think it struck such a chord?

“I think it is the grossness, and the size above all,” she says. “I was talking about the display to another curator and she suggested that basically I had designed the perfect exhibition for teenage boys.” The name is also critical; the Museum of London has added an exclamation mark for effect. “If you can’t use an exclamation mark with a fatberg, when can you?”

I wonder if she would like to see the fatberg in the permanent collection, taking its place as a defining monument to our age of waste. She suggests it remains to be seen. “If it goes on display and ends up as a pile of dead flies then ultimately it has no display value obviously.” In the meantime, for five months, museum-goers can look on this unnatural wonder and perhaps reflect that a culture is most clearly understood from the things it makes and the traces that it leaves behind. As Ozymandias once observed: “Look on my Works, Ye mighty, And despair!”

Fatberg! goes on display at the Museum of London from 9 Feb as part of the City Now City Future season