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Science, Maths & Technology

How London got its Victorian sewers

Updated Friday, 30th August 2019

Recently, there has been a major upgrade to London’s sewer network. But how did the existing system come into existence?

1858 – A city in crisis

The first two weeks of June 1858 were exceptionally hot. That weather led to desperate politicians voting a bill for a complete new sewage system for London through both Houses of Parliament in only 18 days. By 2 August they had approved an Act of Parliament for the expenditure of £2.5 million (about £300 million in today’s money) – and it was to be publicly financed.

Fleet Sewer Creative commons image Icon under Creative Commons BY-ND 4.0 license A cast iron section of tunnel retrofitted to carry the Fleet Sewer across the Metropolitan Railway

Why were they so desperate?

The answer was the threat of water-borne disease and nowhere was this more urgent than in the brand new Houses of Parliament.

London was a rapidly growing city with a population that had reached two million by 1840, having doubled since the beginning of the century and it had a big sewage problem. Before the construction of proper sewers, most of London’s sewage was recycled as fertilizer. Individual houses had cesspools (though often these were just the cellars). The solid waste or ‘night-soil’ was collected from these by well-paid ‘nightmen’ (they were only allowed to work at night) who transported it to the market gardens surrounding the city. The wastewater either seeped into the ground or flowed through the streets into the old natural rivers, which had become public sewers. These all eventually flowed out into the River Thames.

London’s water supply problem

Supplying clean drinking water was another serious problem. Some of London’s water came from shallow wells within the city and was delivered by the bucketful. More prosperous areas had piped water provided by private water companies from springs in the hills around London or, most dangerously, from the Thames itself.

The invention of the flush toilet or water closet at the end of the eighteenth century made things worse. Well-off households that could afford a proper water supply could now dispense with a smelly cesspool and simply flush all their waste away – and out into the Thames.

Cholera arrives

The image is a black and white cartoon called Copyright free  image Icon Copyright free: Public domain Death rows on the polluted River Thames in a cartoon from Punch Magazine (1858)

Cholera is a deadly disease. The primary symptom is acute diarrhoea, which drains the body of nutrients and fluids. In 1831, there was a global outbreak. It had originated in India but had spread across Europe and arrived in Britain. This outbreak killed over 6000 people in London. At the time, the cause of the disease was a mystery. 

The link between the disease and the contamination of drinking water by human sewage was suspected by some. It was obvious that Thames water, when seen through a microscope, was far from clean and it was a subject of wonderful campaigning cartoons in the London newspapers and the satirical magazine Punch.

However, at this time the dominant opinion was the 'miasmatic theory', that the disease was spread by 'fould air'. It wasn't the polluted water that was deadly, but the very smell of it.

A drop of London water - a satirical cartoon by Punch magazine (1850) Copyright free  image Icon Copyright free: Public domain A cartoon of the imagined content of a drop of London water by Punch magazine (1850)

Would the Houses of Parliament have to be abandoned?

Nowhere was this problem more urgent than in the brand new Houses of Parliament.

Construction had started in 1840 following a disastrous fire which had destroyed most of the old Palace of Westminster in 1834. The lavish new building was initially estimated to cost about £700,000 but ended up costing three times as much. By the summer of 1858, the building was almost complete (and the money spent). 

The Houses of Parliament The Houses of Parliament, that were being completed in 1858, could hardly be closer to the Thames

Joseph Bazalgette reviews the options

There was no shortage of ‘solutions’. In 1848 the government had established a Metropolitan Commission of Sewers. After issuing a general invitation to engineers to submit proposals for dealing with London’s sewage, an engineer with a background in land drainage methods, Joseph Bazalgette, was hired.
In 1855, the Metropolitan Local Management Bill was put through Parliament. This attempted to centralise some aspects of the administration of London. It created the Metropolitan Board of Works, one of whose duties was to ‘make such sewers and works as they may think necessary for preventing all and any part of the sewage of the Metropolis from flowing into the River Thames in or near the Metropolis'.

Joseph Bazalgette was appointed chief engineer for the Board of Works. He took his duties very seriously, reviewing 137 different proposals and producing a detailed plan for a scheme of intercepting sewers collecting London’s sewage and discharging it into the Thames 10 miles further downstream (which could be interpreted as being ‘near the Metropolis’). 

The ‘Great Stink’ forces action

The weather of the first two weeks of June 1858 was exceptionally warm, and the River Thames was extremely smelly. Nowhere was it more unpleasant than in the Houses of Parliament. Sheets soaked in disinfectant were hung up to disguise the smell, but it was increasingly obvious that something serious would have to be done. Otherwise Parliament would have to relocate upstream (and out of London).

The ‘force of sheer stench’ (as the Times newspaper put it) prompted the government to act. On 15 July Benjamin Disraeli, as Leader of the House of Commons, introduced a new bill in Parliament, the Metropolis Local Management Amendment Bill. 

One key element was to reword the 1855 Act so that the sewage system would be for ‘preventing as far as may be practicable, the sewage of the Metropolis from passing into the River Thames within the Metropolis’. These extra words, ‘as far as may be practicable’ immediately allowed Bazalgette's proposed scheme to be used. 

The bill was debated for three days and became law on August 2nd. Only 18 days after the bill had been introduced and two months after the ‘Great Stink’ the required Act of Parliament was put in place for Bazalgette to start work.

Bazalgette’s engineering masterpiece

Bazalgette’s scheme was an extraordinary feat of engineering. It involved the construction of major new ‘intercepting sewers’ that would collect sewage from the existing piecemeal array of sewers and move it down river. On the north bank, sewage would be carried eastwards as far as Beckton, eight miles east of St Paul's Cathedral, to be stored and then discharged on the outgoing tide. On the south bank, the sewage would flow as far as Crossness, two miles further downstream, where the same would happen. 

Bazalgette’s system of intercepting sewers A map of Bazalgette's 1858 scheme

Most of the scheme was very carefully designed to flow by gravity, but at critical points, all of the sewage would have to be pumped to a higher level using huge steam pumps. Those installed at Deptford in 1864 were at the time the largest ever built.

One of these pumping stations was at Abbey Mills, where much of the sewage from London’s East End had to be pumped up into the enormous Northern Outfall Sewer which flowed across the marshland towards the discharge point at Beckton. This was a prestige project and the buildings above ground, such as the pumping stations, were lavishly decorated.

The image is of Creative commons image Icon sarahtarno under Creative Commons BY-NC-ND 4.0 license The restored interior of the pumping station at Crossness

Bazalgette replaced 165 miles of old sewers as well as constructing 1100 miles of new ones. It required the excavation of 3.5 million cubic yards of earth by hand – there were no mechanical diggers at the time. The construction consumed 318 million bricks and demand was such that it forced up the price of them in London by about 50%. 

The need for more bricklayers meant that wages had to be increased from 5 shillings (25 pence) per day to 6 shillings (30 pence) or more. It consumed nearly a million cubic yards of concrete. A special mill was built at Crossness to produce this, together with a railway to distribute it

The project made pioneering use of Portland cement, which was water resistant, rather than conventional lime mortar. Because its manufacturing process was so new, Bazalgette insisted on a draconian regime of quality control, with every batch being tested before it was used.

The southern drainage scheme was completed in 1865 and the northern one in 1868. Most of the pumping stations were opened by Royalty, and some of the enormous sewage pumps were even named after members of the royal family.

Joseph Bazalgette was knighted for his considerable services to London in 1874 and retired in 1889, dying in Wimbledon two years later.

Joseph Bazalgette Creative commons image Icon Steven Vacher under Creative Commons BY-NC-ND 4.0 license A memorial to Sir Joseph Bazalgette on Victoria Embankment, London

But you’re still dumping all the sewage in the Thames!

Bazalgette’s scheme moved London’s sewage ‘out of sight’ (and smelling distance) of Parliament but it still dumped it into the Thames. A steady tide of complaints now came from those downstream. 

One particularly nasty incident in 1878 focused attention on the state of the river. The pleasure steamer Princess Alice collided with a freighter and sank near the outfalls, with the loss of 600 lives. There were suggestions that many of the dead had been poisoned by the river water rather than simply drowning.

Pressure from MPs in the 1880s forced the first ‘treatment’ of the sewage. The solid waste was settled out at Beckton and Crossness and only the liquid waste was discharged into the Thames. There were attempts to sell the solid sludge as fertiliser but there was little demand. So in 1887, a fleet of six sludge vessels were commissioned. These sailed down the Thames and dumped it out at sea. Even this is now regarded as unacceptable and was prohibited by an EU Directive in 1998. 

The proper recycling of sewage as a potential fertilizer remains as interesting a challenge today as it was in the 1850s.






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