150 years on from the 'Great Stink' - London needs sewers fit for the 21st Century

Jul 01, 2008

The River Thames is one of the cleanest metropolitan rivers in the world, home to 120 species of fish and aquatic life. However, without the vision of the Victorians, who designed the sewer system that still serves London today, things would have been so much different. Now, 150 years on, the next phase of the evolution of the sewers is about to begin.

Exactly  150  years  ago  to the day, all London's sewage was being flushed directly  into  the  Thames  every day  - around 149 million tonnes a year. Cholera  and  typhoid were striking down Londoners in their thousands. On a blazing summer day, the stench from the Thames was so overpowering that MPs vacated  a  committee room because of the 'great stink'. Amid uproar in the Commons, Parliament was suspended and Members demanded action.

"A  moral  responsibility  lies upon us to do all in our power to prevent a public  disaster," said the Chancellor, Benjamin Disraeli. And in the House of Lords, tempers were running high:

"We  have  now  arrived  at  such  a point that we might expect, not simply typhus  or  cholera,  but a second plague, if the nuisance continues", said the Duke of Newcastle.

In less than two months, Parliament had passed an enabling Act to raise the £3  million  to  build  a  network of giant intercepting sewers and pumping stations. The plans were the brainchild of one of the greatest engineers of the  Victorian age, Joseph Bazalgette, who is today credited for helping to banish cholera and save the lives of tens of thousands in the process.

The  sewers  still  serve  London  today,  together  with  later additions, including treatment works. But  the  combined  pressures  of  population  growth,  climate  change and changing lifestyles are now putting the system under strain.

Imagine  the  population  of London flushing their toilet at the same time. Now  multiply  this  by  850.  That's the amount of dilute sewage currently swept into the Thames every year or 32 million tonnes.*

David  Owens, Chief Executive of Thames Water, which treats all of London's sewage and manages the network of thousands of miles of sewers, said:
"London's  sewers are one of the great engineering wonders of the Victorian age,  and  have  served  us well for 150 years. Bazalgette designed them to overflow  into the River Thames during occasional heavy storms and although this  had  an environmental impact on the river, the alternative of letting sewage overflow into homes and streets, was unthinkable.

"Bazalgette's   design,   perfectly   acceptable   for  a  river  that  was biologically  dead,  would  have been unacceptable today. Now the overflows are increasing in frequency and impact, and we have to act.

"The  Government  has given the go-ahead for us to build the Thames Tideway Tunnel,  a  massive  intercepting  sewer,  running from Hammersmith in West London,  to  Beckton in the east. Earlier this month we submitted plans for the  smaller  Lee  Tunnel,  which  will intercept sewage overflows into the River Lee. Together with our £400million programme of investment to improve our major sewage treatment works, this marks the final step in Bazalgette's grand  plan and will help us deliver a sewage system for London fit for the 21st Century and beyond."

Boris Johnson, Mayor of London said: "On  the  anniversary of the 'Great Stink', it is an opportune time to look ahead  to  how  we  ensure  London  is never again forced to deal with such extreme  consequences of sewage in the Thames. The swift progression of the Thames  Tideway  sewer is vital to avoid the dumping of raw sewage into the capital's  river,  jeopardising our health, polluting wildlife and damaging the  recreational  use  of the Thames. Future generations of Londoners will thank  us  for taking forward this bold vision, in the same way that we are remembering Joseph Bazalgette today."

Clive Coley, of the Environment Agency, said: "The Great Stink taught us a valuable lesson about what can happen when we abuse our environment.  We have worked hard to improve the river for people and wildlife over many years.

"Once the Tideway Tunnel is in operation, we can truly say that our world class capital has 21 Century sewage system and a river that can be enjoyed to its full potential."

* The annual combined sewer overflow for London is 32 million tonnes. Assuming the density of dilute sewage is equivalent to that of water, I kg is equivalent to 1 litre, thus the volume in litres is 32 billion litres. The average toilet flush is equivalent to 5 litres of dilute sewage. The population of London is approximately 7.5million, therefore our combined sewer outfall is equivalent to everyone in London flushing their toilet more than 850 times (853.3).

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