View source for London sewer system

{{Short description|English infrastructure system}}
{{use dmy dates|date=July 2016}}
{{Use British English|date=July 2016}}
[[File:Hering lon-sewer-det02 1882.jpg|thumb|310px|Map of the London sewerage system in 1882]]

The '''London sewer system''' is part of the [[water infrastructure]] serving [[London]], England. The modern system was developed during the late 19th century, and as London has grown the system has been expanded. It is currently owned and operated by [[Thames Water]] and serves almost all of [[Greater London]].

==History==
During the early 19th century the [[River Thames]] was an open sewer, with disastrous consequences for public health in [[London]], including [[cholera]] epidemics.<ref name="Wonder"/> These were caused by [[enterotoxin]]-producing strains of the bacterium ''[[Vibrio cholerae]]''. Although the contamination of the water supply was correctly diagnosed by [[John Snow (physician)|Dr John Snow]] in 1849 as the method of communication, up to the outbreak of 1866 it was believed that [[Miasma theory|miasma]], or bad air, was responsible.<ref>{{Cite book
 | title = Seven Wonders of the Industrial World
 | last = Cadbury | first = Deborah
 | year = 2003
 | publisher = Fourth Estate | location = London and New York
 | pages = 165–6, 189–192
}}</ref> Proposals to modernise the sewerage system had been made in the early 1700s but the costs of such a project deterred progress. Further proposals followed in 1856, but were again neglected due to the costs. However, after the [[Great Stink]] of 1858, [[Parliament of the United Kingdom|Parliament]] realised the urgency of the problem and resolved to create a modern sewerage system.{{sfn|Abellán|2017|p=9}}

[[File:The Prince of Wales opening the Metropolitan Main-drainage works at Crossness, ILN, 1865.JPG|thumb|upright|[[Edward VII|Edward, Prince of Wales]] on 15 April 1865 opening Bazalgette's [[Crossness Pumping Station]]]]
[[Joseph Bazalgette]], a [[civil engineer]] and Chief Engineer of the [[Metropolitan Board of Works]], was given responsibility for the work.<ref name="Wonder">{{cite news |title=Story of cities #14: London's Great Stink heralds a wonder of the industrial world |url=https://www.theguardian.com/cities/2016/apr/04/story-cities-14-london-great-stink-river-thames-joseph-bazalgette-sewage-system |access-date=19 April 2025 |work=The Guardian}}</ref> The [[BBC]] states, "Bazalgette drove himself to the limits in realising his subterranean dream".<ref>{{cite news |title=London Sewers - Seven Wonders |url=https://www.bbc.co.uk/england/sevenwonders/london/sewers_mm/index.shtml |access-date=19 April 2025 |publisher=BBC}}</ref> He and his colleagues, including [[William Haywood (engineer)|William Haywood]], designed an extensive underground sewerage system that diverted waste to the [[Thames Estuary]], downstream of the main centre of population. Six main interceptor sewers, totalling almost {{convert|100|mi|km}} in length, were constructed, some incorporating stretches of [[Subterranean rivers of London|London's "lost" rivers]]. Three of these sewers were north of the river, the southernmost, low-level one being incorporated in the [[Thames Embankment]]. The Embankment also allowed new roads, new public gardens, and the [[Circle line (London Underground)|Circle line]] of the [[London Underground]]. [[Victoria Embankment]] was finally officially opened on 13 July 1870.{{sfn|Cadbury|2003|pp=194–196}}<ref name=Baker>{{Cite book
 | title = Discovering London Statues and Monuments
 | last1 = Baker | first1 = Margaret
 | publisher = Osprey Publishing
 | page = 125
 | date = 2002
 | isbn = 9780747804956
}}</ref>

The intercepting sewers, constructed between 1859 and 1865, were fed by {{convert|450|mi|km}} of main sewers that, in turn, conveyed the contents of some {{convert|13,000|mi|km}} of smaller local sewers. Construction of the interceptor system required 318&nbsp;million bricks, {{convert|2.7e6|m3}} of excavated earth and {{convert|670,000|m3}} of [[concrete]].<ref>Goodman, David C. and Chant, Colin (1999). ''European Cities and Technology'' (London: Routledge).</ref> The innovative use of [[Portland cement]] strengthened the tunnels, which were in good order 150&nbsp;years later.{{sfn|Cadbury|2003|p=183}}

[[Gravity]] allows the sewage to flow eastwards, but in places such as [[Chelsea, London|Chelsea]], [[Deptford pumping station|Deptford]] and [[Abbey Mills Pumping Station|Abbey Mills]], pumping stations were built to raise the water and provide sufficient flow. Many sewers north of the Thames feed into the [[Northern Outfall Sewer]], which transports sewage to [[Beckton Sewage Treatment Works]]. South of the river, the [[Southern Outfall Sewer]] extends to a similar facility at [[Crossness Sewage Treatment Works|Crossness]]. Smaller sewage treatment plants also serve areas further away from central London, such as at [[Mogden Sewage Treatment Works|Mogden]] and [[Deephams Sewage Treatment Works|Edmonton]].

In the late 19th century, William Dibdin, chief chemist for the MBW, conceived the biological [[Sewage treatment#History|treatment of sewage]] to oxidize the waste.<ref>{{cite journal |last1=Hamlin |first1=Christopher |title=William Dibdin and the Idea of Biological Sewage Treatment |journal=Technology and Culture|publisher=Johns Hopkins University Press |date=1988 |volume=29 |issue=2 |pages=189–218 |doi=10.1353/tech.1988.0136 |url=https://muse.jhu.edu/article/889247|url-access=subscription }}</ref> During the 20th century, major improvements were made to the sewerage system and to the sewage treatment provision to substantially reduce pollution of the Thames Estuary and the [[North Sea]]. The sewage works, from west to east, discharging into the tidal Thames in 1950-53 were:<ref>{{Cite book |last=Department of Scientific and Industrial Research |title=Effects of Polluting Discharges on the Thames Estuary |publisher=HMSO |year=1964 |location=London |pages=82}}</ref>
{| class="wikitable"
|+Sewage works discharging into the tidal Thames (1950–53)
!Sewage works
!Miles from London Bridge
!Flow, million gallons per day
|-
|Ham
|17.3 above
|0.15
|-
|Mogden
|15.0
|83.2
|-
|Richmond
|12.1
|5.7
|-
|Acton
|9.8
|3.1
|-
|Beckton
|11.4 below
|190.0
|-
|East Ham
|11.7
|4.5
|-
|Crossness
|13.6
|96.5
|-
|Dagenham
|15.1
|8.8
|-
|West Kent
|19.4
|22.6
|-
|Stone
|20.9
|0.3
|-
|Swanscombe
|22.2
|0.2
|-
|Northfleet
|24.8
|0.6
|-
|Tilbury
|27.0
|2.8
|-
|Gravesend
|27.8
|1.2
|-
|Stanford-le-Hope
|32.1
|0.4
|-
|Corringham
|35.8
|0.15
|-
|Nevendon
|35.8
|0.0
|-
|Pitsea
|35.8
|0.15
|-
|Canvey Island
|37.1
|0.15
|-
|South Benfleet
|40.0
|0.25
|-
|Leigh-on-Sea
|40.0
|0.45
|-
|Southend-on-Sea
|44.6
|6.6
|}

==Modern development needs==
[[File:New abbey mills pumping station.jpg|thumb|The new Abbey Mills Pumping Station]]
The original system was designed to cope with {{convert|6.5|mm|in|frac=4|abbr=on}} per hour of rainfall within the catchment area, and supported a smaller population than today's. London's growth has put pressure on the capacity of the sewerage system. During storms, for example, high levels of rainfall (in excess of 6&nbsp;mm per hour) in a short period of time can overwhelm the system. Sewers and treatment works are unable to cope with the large volumes of rainwater entering the system. Rainwater mixes with sewage in [[combined sewer]]s and excess mixed water is discharged into the Thames. If this does not happen quickly enough, localised flooding occurs (surcharge). Such [[sanitary sewer overflow]] can mean streets becoming flooded with a mixture of water and sewage, causing a health risk.{{citation needed|date=January 2024}}

In redeveloping the [[Isle of Dogs]] and [[Royal Docks]] areas of east London during the late 1980s and early 1990s, the [[London Docklands Development Corporation]] invested in major new drainage infrastructure to manage future sewage and surface water run-off from proposed developments. Consulting engineer [[Halcrow Group Limited|Sir William Halcrow & Partners]] designed a system of large diameter tunnels served by new pumping stations. In the Royal Docks, approximately {{convert|16|mi|km}} of foul and surface water drains were built, plus pumping stations at Tidal Basin (designed by [[Richard Rogers]] Partnership) and [[North Woolwich]] (architect: [[Nicholas Grimshaw]]).<ref>[http://www.lddc-history.org.uk/royals/index.html Royal Docks], LDDC Completion Booklet, 1998</ref> The Isle of Dogs drainage network is served by [[Isle of Dogs Pumping Station|a stormwater pumping station]] situated in Stewart Street, designed by [[John Outram]] Associates.<ref>[http://www.johnoutram.com/iodmenu.html "Pumping Station" – An 'Architectural Primer'], John Outram. Retrieved 2011-09-30.<!-- Notability confirmed by mention of all "three notable pumping stations" in http://www.ribajournal.com/index.php/feature/article/in_the_pink2/ - "In the Pink", RIBA journal, 24.02.2011 --></ref>

===Thames Tideway Tunnel===
{{main|Thames Tideway Tunnel}}
[[File:Thames Tideway construction site, Putney.jpg|thumb|[[Thames Tideway Scheme]] construction site, [[Putney]], 2021]]

The need to handle increasing amounts of sewage, being dumped via sewer overflows directly into the Thames untreated during storms, led to studies being conducted in 2001. After some years of deliberation, the [[Thames Tideway Tunnel]] was approved in 2014. It consists of a wide diameter (7.2 m) storage-and-transfer tunnel, 25&nbsp;km long, underneath the riverbed of the Thames. The tunnel runs between [[Acton, London|Acton]] in the west and the [[Lee Tunnel]] in the east, the latter connecting directly to [[Beckton Sewage Treatment Works]]. The cost of the [[megaproject]] was £5 billion and it was completed in February 2025.<ref>{{cite web |url=https://www.bbc.com/news/articles/cvg875g71lvo |title=London's new super sewer now fully connected |last=Reed |first=Steve |website=BBC |date=February 14, 2025 |access-date=March 28, 2025 |url-status=live |archive-url=https://web.archive.org/web/20250321151901/https://www.bbc.com/news/articles/cvg875g71lvo |archive-date=March 21, 2025}}</ref>

==Literary or media references==
{{More citations needed|1=section|date=July 2023}}
* The system plays a part in English [[The Great Mouse Detective|writer]] [[Neil Gaiman]]'s 1996 novel ''[[Neverwhere]]''.
* The system plays a part in Australian writer [[Michael Robotham]]'s 2005 novel ''[[Lost (Australian novel)|Lost]]'' (a.k.a. ''The Drowning Man'').
* It featured as one of the ''[[Seven Wonders of the Industrial World]]'' in the BBC television series of the same name.
* [[Eleanor Updale]]'s ''[[Montmorency/ Scarper|Montmorency]]'' (beginning with ''Montmorency: Liar Thief Gentleman?'') novels are set against the backdrop of construction of the London sewerage system.
* The construction of the London sewer system is central to the plot of [[Anne Perry]]'s 2006 novel ''Dark Assassin'', in which the Great Stink is also mentioned.
* The title character from Terry Pratchett's ''[[Dodger (novel)|Dodger]]'', based on the [[Artful Dodger]] from ''[[Oliver Twist]]'', spends much of his time in London's sewers alongside notable historical figures including Bazalgette.
*A BBC documentary entitled ''The Five Billion Pound Super Sewer'' focuses on the [[Thames Tideway Scheme]].
*[[Charles Palliser]]'s novel ''[[The Quincunx]]'' features the old, pre-Bazalgette London sewers of the early nineteenth century in an extensive sub-plot.
*The sewer system served as the hideout of Professor Ratigan in Disney's 1986 film ''[[The Great Mouse Detective]]''.

==See also==
* [[Fatberg]]
* [[Medical Officer of Health for London]]
* [[Metropolitan Commission of Sewers]]
* [[Tosher]]

==References==
{{Reflist|30em}}

==Bibliography==
{{refbegin}}
*{{cite conference |url=https://www.researchgate.net/publication/319623260 |title=Water supply and sanitation services in modern Europe: developments in 19th-20th centuries |last1=Abellán |first1=Javier |date=2017 |location=University of Salamanca |conference=12th International Conference of the Spanish Association of Economic History }}
*{{Cite book |last=Johnson |first=Steven |authorlink=Steven Johnson (author) |title=Extra Life |publisher=[[Riverhead Books]] |year=2021 |isbn=978-0-525-53885-1 |edition=1st |pages=79 |language=en}}
* Skilton, David (2007) ‘"Sweet Thames, run softly": the Construction of a Clean River’, ''Literary London Journal'' 5 (March 2007) {{ISSN|1744-0807}}. http://literarylondon.org/the-literary-london-journal/archive-of-the-literary-london-journal/issue-5-1/
* Trench, R. and Hillman, E. (1984) ''London Under London: A Subterranean Guide'' (London: John Murray).
{{refend}}

==External links==
* [https://www.museumoflondon.org.uk/discover/how-bazalgette-built-londons-first-super-sewer  "How Bazalgette built London's first super-sewer," by Alwyn Collinson, 26 March 2019, Museum of London]
* [https://pmj.bmj.com/content/77/914/802 "Construction of London's Victorian sewers: the vital role of Joseph Bazalgette," by G C Cook, The Fellowship of Postgraduate Medicine] 
* [https://www.theguardian.com/waste/story/0,12188,1447785,00.html Tales of the underworld] from [[The Guardian]] Wednesday 30 March 2005

{{Water supply and sanitation in London}}
{{Thames Water}}
{{Metropolitan Board of Works}}
{{London history}}

[[Category:London water infrastructure]]
[[Category:Metropolitan Board of Works]]
[[Category:Sewerage]]
[[Category:Subterranean London]]
[[Category:Thames Water]]