We’re going underground again today, into a tunnel network that Londoners use many times a day, yet never see. At a time when waste water problems are so often in the news, I thought it would be timely to recall some of my own trips into the sewers, alongside their fascinating, faeculent history.
📣📣 First a quick announcement… fancy a pint and a chinwag about London history with fellow enthusiasts? We’re holding another meetup in an historic London pub on 1 May… probably one of the Wapping pubs. Note, this is open to paying subscribers only (see options on the button below if you’re not a paying subscriber). Drop me a line if you’d like to come along, on matt@londonist.com, and I’ll supply more details.
Into the Sewers: Exploring London’s Historic Bowels
“What does it smell like?”
It’s the knee-jerk question if you say you’ve been down a sewer. Everyone asks it.
To get that one out of the way early… well, it’s not all that bad. You know that musty smell from damp laundry that’s been left in a heap too long? Imagine that magnified ten-fold, with a subtle, faecal twist. I’ve been in three live sewers, and all had that consistent odour.
I didn’t spend long considering the aromas on my first visit in 2010. As a noviciate sewer tourist, every gram of concentration went into keeping my balance. I was knee deep in cackish, flowing water. My legs were protected by waders that filled with air, introducing an unwelcome buoyancy below my centre of gravity. Several kilos of emergency breathing apparatus tugged on my shoulders. Below the foetid churn, my boots slid on a soft mat of best-not-think-about-it. With all this going on, I simply lacked the bandwidth to consider the smell.
I lost my sewer virginity to the queen of them all, the Northern Outfall Sewer. This autobahn of filth flows west to east, from Hackney Wick to Beckton. It clears most of the crap from north London. You may have walked along it yourself. Above ground, its a well-trodden footpath known as the Greenway. Below ground, it’s a smell-ridden poopbath known as the Brownway.
How does one dress for an amble through a sewer? Everyone must wear the full kit of protective gear: crotch-high waders, super-thick socks, a billowing paper suit to guard against random splashes, a hard hat, rubber gloves, a safety harness for ladder climbing and a portable oxygen cylinder in case of gas buildup. Beneath all that, the professionals, known colloquially as flushers, wear little but their underwear - it can get pretty stuffy down beneath. It’s the flusher's job to inspect the hundreds of miles of sewer, and relieve blockages, such as the notorious ‘fatbergs’ of cooking fat, tissue and other stuff that shouldn’t have gone down the toilet. They’re heroes, really.
I descended at Wick Lane, one of the great sewerage meeting points, where the detritus of north London combines into the five parallel chambers of the Northern Outfall, and thence to the epic treatment works beyond the Royal Docks. This vast, brick-lined cloaca carries the entire anal output of Hampstead, Hackney and Haringey. Arsenal’s arse-balls and Tottenham’s hot turds float side by side toward the filter beds of Beckton. The commingled taupe tide has not ebbed in 150 years.
Built to last
The Northern Outfall and its sibling sewers were conceived in the hot summer of 1858. By this time, London was the largest city in the world, with three million souls evacuating their bowels into an antiquated sewer system built for a much smaller population. Many Londoners now used flushing toilets, which further increased the volumes. Meanwhile, a rise in noxious industries added to the — shall we say —character of the effluent. Almost all of this foul overspill ended up in the Thames. It honked so much that it was given a name: the Great Stink. London’s recent cholera outbreaks were blamed on the miasma from the Thames1.
Step forward the civil engineer Joseph Bazalgette who, with the Metropolitan Board of Works, came up with a robust plan for dealing with the filth. Over the next 20 years or so, he built over 100 miles of interceptor sewer, the largest of which are shown in red on the map up top, as well as many smaller connecting tunnels. It’s been estimated that the project required 318 million bricks, which I reckon would be enough to build 53 Battersea Power Stations. The most visible addition was the Victoria Embankment, reclaimed land which not only carries an interceptor sewer, but also a major road, the Circle/District line and numerous utilities.
The new sewers ushered the waste away from the population centre by gravity, with two ornate pumping stations at Abbey Mills (north) and Crossness (south) helping things along. The captured sewage from the north eventually found its way to Beckton where it was pumped, untreated, into the Thames on the ebb tide.
I think this is an under-appreciated facet of the Bazalgette scheme. It didn’t stop the crap getting into the river at all — it merely shifted things downriver away from prying noses. This decision had ghastly consequences in 1878, when the paddle steamer SS Princess Alice collided with a coal ship near Beckton, minutes after 75 million gallons of raw sewage had entered the Thames. More than 600 people died that night, making it the worst single disaster in London’s recorded history. Another 16 of the rescued died later from the effects of ingesting tainted water. It would take decades before London’s sewage would be properly treated.
Into the Fleet
One sewer that predates Bazalgette’s schemes by a hundred years is that containing the River Fleet. This ancient river flowed from Hampstead Heath to King’s Cross, thence down Farringdon Road and Street to debouch at Blackfriars. It still follows that route, but in a sewer whose lower sections were enclosed from the 1730s. Rather than spilling into the Thames, it’s caught by Bazalgette’s interceptor beneath the Embankment.
I took a paddle through the section beneath Farringdon Street in 20102. This was a very different beast to the Northern Outfall, much narrower and shallower, but built high to increase capacity.
You’ll note the orange breathing equipment over my shoulder. This is mandatory for anyone entering the sewers. Many people have lost their lives to noxious gas build up. During one incident in 1849, three workers and two would-be-rescuers were killed in a sewer beneath Warwick Street, Pimlico, after inhaling hydro-sulphate of ammonia and carbonic acid. Flow rates are much higher today, reducing the chance of gas build-up, but it’s still considered a significant enough risk that heavy oxygen canisters are carried by all workers.
Sewers, it turns out, are not featureless pipes but are replete with interest. Small side channels feed in at regular intervals, with contributions from adjacent properties and (on rainy days) run-off from the street. A series of iron hoops decorate either wall of the Fleet sewer at this point. The flushers told me that these hoops date from times when the Fleet was an open-air river, and were used for securing barges. This seems somewhat unlikely, given that this section of Fleet was largely covered over almost 300 years ago.
My short trek ‘upriver’ led to a bifurcation point, somewhere beneath Holborn Viaduct. Here the main Fleet sewer divides in two, for reasons no one seems quite sure about, before recombining at Ludgate Circus. I suspect this was to better support the buildings of Fleet Market, which was constructed in two rows above the newly-roofed culvert.
I returned to the Fleet in 2015, this time in the company of film-maker Geoff Marshall and ‘lost river’ expert Tom Bolton. Like three cautious hobbits we descended into a narrower part of the Fleet Sewer, ‘upstream’ beneath the streets of Camden. Here’s the video:
Looking to the future
As I often say, on Londonist: Time Machine we like to dip into the future, as well as the past. And no article about London’s sewers would be complete without some discussion of the present state of the city’s sewage, and what’s to come next.
As anyone living in Britain today knows, our rivers and seas are awash with sewage. The problem isn’t close to the levels seen during the Great Stink but, nevertheless, the dumping of raw effluent is a major issue.
Part of the problem, in London at least, is another boom in population. Bazalgette had, he thought, future-proofed his sewers by building them large enough to handle a doubling of population. It’s since trebled. At the same time, much more of our land is now paved over, giving rain water nowhere to go but into the drains, there to mix with the brown stuff. When the system reaches capacity, it discharges into the Thames, poops and all. And that happened almost 1,200 times in 2023.
To address the problem, Thames Water has spent years constructing new interceptor sewers. The best known is the Thames Tideway, a 25km-long tunnel deep beneath the Thames, into which overspill will pour. It should stop about 95% of discharges (more info here). Major construction is now complete, but it’ll take a year or two of testing and tweaking before it can be brought into service. You can’t polish a turd, but you can buff its surroundings.
I was lucky enough to get a peek inside the section near Battersea Power Station last year. It’s truly gigantic. The main tunnel is a metre wider than the Elizabeth line — wide enough to park three double-deckers side by side, as the PR team are fond of pointing out.
This supersewer has been much publicised. Less well-known is the Lee Tunnel, another new relief sewer, which takes much of the crap that would otherwise flow into the River Lea. This is London’s deepest tunnel, 75 metres below ground and more than a mile long. It’s so big, in fact, that the construction team ran a temporary railway through the tunnel. I went along with Geoff Marshall in 2015 to get a look at this uncelebrated tube, before it received its brown filling a year later:
The modern sewers are engineering marvels, and much needed. But they’ll never evoke the same wonder as the Bazalgette-era brick tunnels. Indeed, they’ll rarely be seen by human eye as they’re designed to operate for years without significant maintenance. There are no flushers in the Lee Tunnel.
While we justifiably bemoan the state of London’s rivers, it’s worth remembering what an awesome job Bazalgette’s 150-year-old sewers did for London, and continue to do. Those 318 million bricks have been exposed to foetid, flowing water for every minute of every day for a century and a half, over which time the city’s population has trebled.
Even with the new super-sewer, tackling London’s waste water will always be a challenge. Climate change is likely to bring heavier and more sustained rain (as we saw over the winter of 2023/2024), and the city’s population is projected to grow still further.
The sewers, then, will continue to drain resources as surely as they drain our homes and streets. But hopefully, when the Thames Tideway is up and running, they’ll carry the sweet smell of success once again. Faecally tainted, of course.
Thanks for reading! As ever, feel free to squeeze out a comment below, or plop something into my inbox on matt@londonist.com. And remember to tell your friends about Londonist: Time Machine… the more subscribers we get, the better it’ll become.
Cholera is, of course, a water-borne disease, and is not transmitted through smell or ‘miasma’. John Snow had good evidence for its true nature, thanks to his well-known intervention at a Soho pump, but his theories were not accepted until many years later.
Also there on that visit was Dan Snow, filming his series Filthy Cities. He went down in the group before mine to get some shots. I think I might have inherited his soiled waders after he came out.
Does anyone else remember the Clerkenwell House of Detenttion when it was open to the public? I think it closed 20+ years ago. I'm pretty sure I remember being told during the tour that some 9f the tunnels we were walking through had been sewers at some point. Not sure if it was true though ...
They had a 10K charity bike ride in the Super Sewer, from Battersea and Blackfriars then back again, last year. Would love to have witnessed that...