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Flushed away: Sewers through history

Published: 2 February 2021

In contemporary British homes, a flushing toilet is a basic expectation. Over time we’ll have thousands of intimate interactions with this hardware—before conveniently flushing and forgetting about our waste.

But what happens after you flush, and how was this essential everyday technology developed? What are the threats to health when we don’t have adequate ways of managing our waste? 

In public health the most important thing is to get rid of sh*t.

Professor Valerie Curtis (2019)

Gross is good? The power of disgust

The feeling of disgust portrayed in Darwin's The Expression of the Emotions in Man and Animals, 1872

Feeling some level of disgust at the look, smell or even thought of our own excrement probably seems obvious, but it serves an essential purpose.

Disgust, proposed the great naturalist Charles Darwin, was among the very basic emotions, one his extensive travels suggested was common to all cultures. Of the potential triggers for such a response, human faeces is one that’s common to all human societies. 

A century on from Darwin, British scientist and self-titled ‘disgustologist’ Professor Valerie Curtis was among those proposing a biological reason for avoiding excrement. Things we find disgusting often make us ill, and faeces can be teeming with dangerous bacteria and viruses. 

Placed in a genetic context, honed by evolution and heightened by social conditioning, this reaction can be seen as an important natural mechanism for self-preservation—an automatic response to the threat of infection and disease.

Fundamentally, whenever our waste management systems are inadequate, our excretions can become a major threat to health—and so, as the human population expanded, our waste problem became too big to simply avoid.

Managing sewage in ancient history

Our very success as a species is part of the problem when it comes to managing human waste. 10,000 years ago, when around five million humans lived on the planet, the excrement they produced was quite easily absorbed. It could be buried, thrown into rivers or used to fertilise an increasing variety of crops.

As larger settlements grew, the constant production of waste became a more significant problem. In response, some ancient cultures developed approaches that were both imaginative and also prefigure elements of the sewage systems we’re familiar with today. 

Purpose-built toilets have been revealed in numerous archaeological excavations. The Mesopotamians, Minoans and Ancient Greeks all developed them for single and communal use. Excavations in the Indus Valley (parts of modern-day Pakistan and northern India) have revealed remains that suggest a number of small sewer systems, which used flowing water to carry waste away to nearby watercourses or into large pits that were periodically cleaned—essentially the same arrangement used in mid-Victorian London, nearly 4,000 years later.

The Romans also developed quite complex sanitary systems. These included sewers through which human waste could be carried away, usually to nearby rivers and streams. The Cloaca Maxima—the most famous Roman sewer—evolved from a layout of open drains into an extensive subterranean passage which snaked beneath Rome itself. Nonetheless, plenty of excrement was still dumped in the streets and other public places. 

Cloaca Maxima images

As these earlier civilisations declined, so too did further innovation in large-scale sewage management. Throughout the Middle Ages, such systems were mainly to be found in the medieval Islamic world, where simple but functional sewer networks existed in a number of urban centres.

By the time Britain began to emerge as an industrialised and increasingly urbanised nation, the management of human waste had become a pressing issue.

Cesspits and early sewers

Social conditioning and our innate sense of disgust means we have long desired at least some privacy when answering the call of nature. As private domestic spaces for doing one’s business became more clearly defined and desired, at least in more affluent dwellings, the question of what to do with all the outpourings remained. 

Pepys quote

...going down my cellar to look, I put my foot into a great heap of turds, by which I find that Mr Turner’s house of office is full and comes into my cellar, which doth trouble me...

Samuel Pepys, Diary entry (20 October 1660)

The famous London diarist Samuel Pepys’ messy encounter with his neighbours’ turds reveals the unpleasant realities of sewage disposal. The ‘house of office’ was then a common name for a toilet, and the cellar was where Pepys shared a cesspit with his neighbour.

Cesspits, or cesspools, were cavities dug into the ground that were ideally brick-lined, into which both liquid and solid human waste were dumped—usually along with other domestic rubbish.

They were often purposely made porous so that the liquid content slowly seeped away and capacity for solid waste was maximised. Even so, they needed to be emptied occasionally and this unenviable task was left to so-called ‘night soil men’ or ‘nightmen’.

Nightmen illustrated in Henry Mayhew's 'London Labour and the London Poor', 1851

They were legally required to do this work at night, exposing fewer residents to the unpleasant sight and unbearable stench. The nightmen would take their laden cart on an odorous route to sell their load as fertiliser to farmers in the nearby countryside. This was a long-standing tradition.

Industrialisation and the need for better sewerage systems

As industrialisation transformed Britain from the mid-1700s, the limitations of these traditional methods for collecting and removing sewage became clear. Urban areas were increasingly crowded, and the nation’s population nearly tripled during the following century. Unfortunately, such revolutionary changes were not reflected in the world of human waste management.

Cesspits continued to be installed in basements or the shared spaces between houses. These would be filled via indoor facilities or from outdoor ‘privies’—shed-like structures containing a toilet, often little more than a wooden seat above a channel leading down to the cesspit. In wealthier homes these might be in the garden, a discreet distance from the house. For the poor living in the ever-expanding slums, one such basic facility could be shared by dozens of households.

Seat from outdoor privy, 1850–1900.
Science Museum Group More information about Seat from outdoor privy, 1850–1900.

The word ‘sewer’ derives from a medieval term for a watercourse that drains away from marshy land or a pond. Inevitably they were increasingly used for carrying away more unpleasant materials, and over time these channels took on the character of sewers as we would recognise them—though without any treatment or managed destination for the waste.

In London, the destination of this waste was almost invariably the River Thames itself. Many residents simply took the short route and deposited their excretions directly into the Thames and its tributaries. Unfortunately, these were also the source of much of the capital’s drinking water—clearly a problem for public health.

Houses in Bermondsey, pictured in 1810. The wooden shacks are privies that emptied directly into a tributary of the River Thames

Bad to worse: The impact of flushing toilets

Diagram showing connected tanks and pipes with labels describing each part Science Museum Group Collection
A detailed illustration and description of a water closet first described by John Harington in 1596.

As a broad concept the flush toilet had a number of ancient precedents, but its ‘modern’ invention is generally credited to the unlikely figure of Sir John Harington.

Aristocrat, author and godson of Elizabeth I, Harington created and installed a flush toilet in the 1590s. It was certainly ingenious, but proved impractical for the times. Requiring huge amounts of water and without a proper sewer system to connect to, it didn’t catch on.

It wasn’t until over two centuries later, in an era of increasing industrialisation and commercialism, that a new generation of appliances became available.

Their growing popularity was hugely boosted through marketing at The Great Exhibition of 1851 and they became a must-have addition to the middle-class home. Although flushing toilets remained an inaccessible luxury for huge swathes of the population until well into the 20th century, designs proliferated from the mid-19th century on.

Model of the 'Optimus' water closet. Invented by Stevens Hellyer in 1870, the Optimus toilet was an improvement on earlier designs, flushing more quietly and efficiently

More information about this object

Flushing toilets gallery

Flushing toilets from our collection:

The arrival of the flushing toilet might sound like a boon for hygiene, but in a city like London, the increasing use of these toilets actually made a bad situation worse. 

The addition of flush water helped overwhelm cesspits, which frequently overflowed and contaminated local water supplies, while those plumbed into the haphazard existing sewers simply polluted the Thames more efficiently. The breaking point was reached in the hot summer months of 1858, when the constant and overwhelming smell of human excrement emanating from the river became known as The Great Stink.

Towards the modern sewer system

The solution to Victorian London’s waste problem was that taken by many urban centres during the 19th century—a vast engineering project to create a coherent and functioning underground sewer network. Primarily designed by engineer Joseph Bazalgette, construction began in 1859, with the bulk of the system completed in less than a decade.

Construction of sewer tunnels near Bow, east London 1859.

It involved replacing or upgrading much of the existing haphazard system and constructing around 1,100 miles of new sewers. These channels then fed the 82 miles of large new ‘intercepting sewers’ with wastewater from various sources, and more solid human waste. Built to a fine gradient, the intercepting sewers slowly took the flow east of the city. There, with the help of a number of cathedral-like pumping stations some miles downstream, it was dumped into the Thames, to be carried out with the tide.

Drawing of a building with lots of windows and spires, flanked by two tall narrow towers Science Museum Group Collection
The Byzantine-style Abbey Mills pumping station at Stratford, 1868.

Bazalgette’s sewers were transformative and a huge boon to public health. Britain did have a final outbreak of cholera in 1866, but the parts of London hit were not yet connected to the new system. Unfortunately, raw human waste was still entering the river—much to the annoyance of communities along the Thames estuary. 

In 1878 the sinking of the pleasure steamer SS Princess Alice where millions of gallons of sewage had just been released, costing 650 lives, brought the problem into sharp relief.

Two continuous columns of decomposed fermenting sewage, hissing like soda-water with baneful gases, so black that the water is stained for miles and discharging a corrupt charnel-house odour, that will be remembered by all.

‘A Pharmaceutical Chemist Writes’, The Times (6 September 1878)

After several years of debate and investigation, it was decided that sewage should receive a basic level of ‘treatment’ before it was discarded. Large tanks were installed near the main pumping stations. There sewage was stored and chemically treated to settle out the solid waste. The liquid part still went in the river, but from 1887 the separated sludge was loaded onto special ships. Soon nicknamed ‘Bovril boats’ due to their sticky brown cargos, these sludge vessels followed a ‘pump and dump’ strategy by releasing the effluent into the open sea. 

Such large-scale maritime waste disposal continued for the following century, using boats or more directly via pipes extending out into the sea. During the 1990s this practice became largely prohibited in UK waters, but the sea remains the major destination for much of the world’s sewage, whether treated or not.

Despite regulatory changes, large amounts of raw home-grown product, replete with human waste, is still released into British seas each year—usually as an emergency measure when systems become overloaded.

Contemporary sewage treatment

In 2013, epidemiologist and author David Waltner-Toews estimated that with over 7 billion people on Earth, around 400 billion kilograms of excrement was being produced annually—more than the weight of 30 million double-decker London buses. By 2023, the population is likely to hit 8 billion.
Across Britain today, when this malodorous waste is flushed away, most of it follows a familiar route. Passing through our domestic pipework it enters the nearest underground sewer pipe, where it joins the flow of wastewater from neighbouring households and street drains. This may then connect to larger tunnels in the network of sewers, gradually transporting it to a sewage treatment works. 

Avonmouth Sewage Treatment Works, which serves Bristol and the surrounding area

Once there, larger objects that have made it that far—such as wet wipes, nappies and plastic wrappers—are removed, as is the huge amount of grit that washes into the system.

Then, as has been the case since the 1880s, the fragmented remains of the local community’s excretions are separated within large settlement tanks. Various solids sink to the bottom to form a sludge which is pumped away for further treatment. What remains of the more fluid element is also treated, settling and filtering and biological breakdown before it can be returned to our systems of rivers and streams.

As for the sludge, since the retirement of Bovril boats, much of it is put to productive use. Echoing traditional practices, some is converted via chemical treatment and heat drying into agricultural fertiliser. It can also be used to generate energy. Heating the sludge causes bacteriological activity to accelerate, breaking down the waste to produce biogas, which can be burned to create heat to produce electricity. Sludge can also be dried into what’s known as ‘cake’, from which electricity can be conjured from the heat produced when burning it. 

Sewage management systems like these are essentially massive, complex engineering projects. They’re also extremely expensive, especially if you’re starting from scratch and rely on plentiful supplies of water. In regions where existing arrangements for human waste disposal are limited and running water may be scarce, alternative off-grid means of sewage disposal have been introduced.

A compost toilet, which uses sawdust to reduce odour and encourage decomposition of waste.

Given the pressures on water and energy resources, there are growing calls to follow the lead being taken elsewhere in the world and simplify such a treatment cycle. In doing so, we may need to learn to overcome that natural sense of disgust, as our drinking water could be piped directly from treatment plants back into our homes, rather than coming back to us via the longer route of streams, rivers and reservoirs. Bottoms up, everybody!

Find out more

  • Stephen Halliday, An Underground Guide to Sewers. Or: down, through & out in Paris, London, New York &c., 2019
  • Stephen Halliday, The Great Stink of London: Sir Joseph Bazalgette and the Cleansing of the Victorian Metropolis, 2001
  • Jamie Benidickson, The Culture of Flushing: A Social and Legal History of Sewage, 2007
  • Ann Olga Koloski-Ostrow, The Archaeology of Sanitation in Roman Italy: Toilets, Sewers, and Water Systems, 2015
  • Richard Trench and Ellis Hillman, London Under London: A Subterranean Guide, 1993