The Sewers of London

Every so often we'll get a whiff of something unsavoury from the sewers below.  This set me thinking about London's Victorian sewer system and whether it is coping with today's population.

The basis of the sewer system in London today was built in the second half of the 19th century. Prior to this, sewerage was dumped straight into the Thames in the middle of the city, contributing to outbreaks of cholera and the death of the river as a habitat for wildlife. During 'The Great Stink' of 1858 the smell from the polluted Thames got so bad that parliament made plans to relocate rather than enduring the stench in the Houses of Parliament on the banks of the river. Fortunately for the politicians the unusually hot weather that exacerbated the smell soon ceased, removing the immediate problem.  

Fortunately for the citizens the Great Stink provided the impetus to improve waste disposal in the city. Cholera was believed to be transmitted through the smell, or 'miasma', of the raw sewerage and waste in the city. It was an unintended consequence that in building the sewers to remove the smell the city's engineers also removed the source of the disease.

The system of sewers was designed by engineer John Bazalgette and constructed by the end of the 1860s.  It transported waste further down the Thames, past the populated area, though it still discharged untreated sewage into the river. It wasn't until the 20th century that treatment plants were constructed and improved the quality of the discharge to the river.

This system is still in use today, 150 years later.  

The sewers appear to have even supported a number of unusual and unpleasant occupations. This article on Smithsonian.com gives a (possibly too) detailed account of the job of a 'tosher'.  A tosher was an unfortunate who earned a living by wading through the sewers collecting things of value, such as lost silverware or coins etc. Apparently they made quite a good living! I think this puts a somewhat stronger spin on the phrase 'oh tosh!'

The capacity of the system, while designed at way above the needs of the time, seems near being reached today. The old system was designed for 4 million people, but there are now over 8 million people in London. During heavy rain storm water runs into the sewer system and the mix overflows into the Thames. I was surprised to read that this happens quite often - around once a week, according to Thameswater. 

The government is in the process of increasing the capacity of the sewer network through building a number of projects including the Thames Tideway Tunnel - a tunnel along the Thames to capture the overflow.  Check out this video for a view inside the tunnels and a bit about the history and the Tideway Tunnel project.

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While browsing the net on this subject I found a number of groups really into the forgotten underground of London.  I think the folk behind sub-urban.com are particularly dedicated - investigating the sewers in chest high waders!