What Creates a Fatberg? 9 Things Found In the South Bank London Fatberg

In 2018, Channel 4 aired a documentary entitled ‘Fatberg Autopsy: Secrets of the Sewers‘ where Thames Water drainage workers, known as flushers, worked with scientists to uncover the truth about what makes up the fatbergs taking over the London sewers. The research, led by mortician Carla Valentine, used forensic techniques normally used in human autopsy to discover what horrors were lurking inside the fatberg.

A five tonnes sample was taken from a discovered fatberg in South Bank estimated to be a minimum of 750 metres in length, dwarfing the previous largest fatberg discovered in London, the Whitechapel fatberg, which measured 250 metres in length. To dismantle the South Bank mammoth, an 8 man team from Thames Water had to manually chip away the fatberg to remove it from the Victorian sewer system which was originally created to serve 4 million people, not the 8 million it currently handles. The population’s love of eating out at restaurants and buying takeaways has no doubt contributed to this with the restaurant district’s sewers the most disturbing as fatbergs quickly form from the deposit of cooking oils. This means the local water authority has to make regular checks of the sewers located nearby which has caused some water authorities to prosecute restaurant owners who fail to install a grease trap at their business and, more importantly, keep it cleaned and maintained to ensure it runs correctly.

When removing a fatberg of these mammoth proportions found in London, flushers have to carry a H2S detector on them which analyses the levels of Hydrogen Sulphide gas in the atmosphere. Produced by the rotting sewage in the sewers, Hydrogen Sulphide can be lethal in high doses so the workers must be alert and vigilant when working on a fatberg in case they need to quickly evacuate the sewer.

What causes a fatberg?

Fatbergs are caused by people flushing things other than toilet paper, poo and pee down the toilet as well as pouring things they shouldn’t down the sink. Over time, these foreign objects and liquids accumulate and can snowball into the enormous, rock-hard deposits now referred to as fatbergs. As you will no doubt have guessed, fat makes up a large proportion of the fatberg and is the main binding component that enables other things to stick to it. What exactly constitutes a fatberg is something the Thames Water flushers and the scientific team led by Carla Valentine set out to discover.

9 Things Found Inside the South Bank Fatberg


Whilst it’s encouraging that men are using protection when having sex, throwing their used condoms down the toilet and flushing them is not the ideal method of disposal. Condoms, used or not, should always be binned and never flushed as these latex-based products do not break down like toilet paper does and can easily form part of a bigger blockage in the sewers.

Tampon Applicators

It’s always advised that tampons and sanitary towels should not be flushed down the toilet due to their absorbent qualities. The fact that they also don’t disintegrate like toilet paper is another reason not to flush. Knowing that the soft materials are not flushable, you would expect that people wouldn’t flush cardboard or plastic tampon applicators either. Tampons and sanitary products should always be disposed of using a sanitary bin or wrapped in tissue and dropped in a regular waste bin if no sanitary waste bin is present.

Drugs Bags

When there’s a risk of being caught, drugs bags can often be flushed down the toilet to avoid the police catching them with narcotics in their possession. Some may also decide to flush a bag after use. Either way, plastic bags, empty or containing drugs, do not belong down the toilet nor in the sewers and only serve to add to the build up of non-degradable waste.

Wet Wipes

One of the main culprits of blockages and fatbergs up and down the country, wet wipes are the bane of any flusher’s life. Unlike toilet tissue, which breaks down really easily, wet wipes, particularly those that are made from plastic-based materials, do not break up in the same way. Some wet wipes don’t even disintegrate at all. Unfortunately, many people are still unaware that these seemingly-harmless wipes can cause so much trouble. What doesn’t help is that some manufacturers label their products as being flush-friendly. However, this is a reference to the fact that they are able to navigate the toilet’s u-bend, not that they will actually disintegrate when flushed.

When it comes to wet wipes or baby wipes, always bin them, never flush!

Syringes & Needles

Syringes were found inside the South Bank fatberg which may allude to the method in which people are disposing of the needles once used. Whilst most people who require prescribed medication via syringe will dispose of their syringes correctly using a sharps box, other individuals, such as drug addicts, are often not as careful or considerate and may flush or dispose of the syringes down the grid in an attempt to get rid of the evidence to avoid being caught. Sometimes, when syringes have been dumped on the ground, people kick them into the grids to get rid of them which ultimately leads the syringes to the mains sewer where they can collect and become part of a congealed blockage.

Syringes should always be disposed of using a sharps box or at a pharmacy. If discovered on the floor of public land, the council should be informed to safely collect and dispose of them. Syringes can be dangerous for drain workers to come into contact with when they’re manually chipping away at a fatberg by hand. Being pricked by a needle can cause serious harm due to the diseases which blood, often found on the needle, can carry.


When dissecting the fatberg, the scientists put some of the samples underneath the microscope to see what diseases, if any, were living inside the fatberg. e.coli, usually found in human and animal intestines, was discovered along with listeria, both of which cause serious illness. More bacteria were found besides these, including antibiotic-resistant superbugs that could prove deadly if they ever reached the population above ground.

Cooking Oil

Cooking oil is the glue that binds the debris to the sewer pipes. Along with fats and grease, oil is one of the most damaging culprits that regular enters the mains sewers.

Though cooking oil may seem harmless to you or I, when cooled it solidifies and that’s not good for your drainage system! Similarly, when fat mixes with calcium in the water supply, it turns to soap. These sticky substances that end up lining the sewers attract other debris that floats down the drains. Together, they combine into a blockage, eventually becoming the enormous fatbergs that occupy mains sewers up and down the country, causing flooding and, in some cases, sewage to back up.

Cooking oil and other fats should never be poured down the sink. They should be poured into a jar and left to cool and solidify before putting in the bin. Cafes, restaurants and other businesses that regularly prepare food should always have a grease trap fitted to prevent any oils and fats entering the drainage system.

Shampoo & Soap Residue

It’s probably no surprise that shampoo and soaps were found inside the fatberg. As we regularly wash our bodies and hair with cleaning products, it’s to be expected that these chemicals enter the mains sewer after draining away down the plughole. Whilst these can contribute a little to fatberg build ups, these are unavoidable from entering the sewers. At least it’s a sign that people are keeping clean!


As our bodies expel waste through faeces and urine, it’s not surprising that the scientists discovered numerous drugs present in the fatberg. These included MDMA, Amphetamines, Morphine, Paracetamol and Ostarine. Whilst Paracetamol is a painkiller which is often used and is readily available from shops, other drugs found were the illegal types such as Class A drug Ecstasy (MDMA) and Class B drug Amphetamine. Ostarine was a surprise inclusion as this is a prohibited drug not fit for human consumption and was only used for research purposes for those suffering from medical conditions that resulted in muscle wastage. However, Ostarine has occasionally been found in shady supplements aimed at bodybuilders and athletes to help them build muscle, though many times its inclusion in the supplement appears to go unlabelled and, in some cases, even the person taking the supplement is unaware of its presence.

If you live in the UK, you can watch Fatberg Autopsy: Secrets of the Sewers on All4

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It’s important to keep your drains healthy which is why bags, sanitary products, condoms, syringes, wet wipes and fats, oil and grease should be kept out of our sewer system. Flushing or pouring something down the drain that doesn’t belong can easily result in a blocked drain in London, or wherever it is you’re based. If you suspect you’ve got a blockage and require your drains cleaning, contact Drain 365 today on 0800 699 0922.