Sir Joseph thought of engineering as an instrument of public welfare, a way of improving the wellbeing of man, and his sewerage system is generally regarded as making the greatest single contribution of its time to Londoners' health. It was all the more remarkable that when he first proposed it, the purported link between polluted drinking water and the cholera epidemics that ravaged London in the 1840s and 50s was believed by only a few. Bazalgette had to find a way of moving the city's effluent far enough down the Thames for it to be taken out to sea by the tide. The existing system simply fed untreated sewage into the river at low tide (the river backed up the sewers at high water), leaving it malodorously swilling back and forth with the current. This was particularly evident during The Great Stink of 1858. At the time the Thames was so polluted that it was devoid of fish.
Bazalgette's answer was a system of sewers carrying the waste eastwards to Barking. It consisted of 83 miles of underground brick main sewers to intercept sewage outflows, and 1100 miles of street sewers, to intercept the raw sewage which up until then flowed freely through the streets and thoroughfares of London. He constructed four huge pumps and the north Thames embankment, under which the northern arm of the sewer runs, together with the tube's Circle line. His indispensable partner was the Metropolitan Board of Works - he was its chief engineer - which saw itself as "the appointed physician to the metropolitan organism."
Decades later, actual sewage treatment facilities were constructed.
The effect of the new sewer system was to reduce cholera not only in places that no longer stank, but wherever water supplies ceased to be contaminated by sewage.
Return to the Sewer History area of the SwopNet Engineering Databank
There you will find Parts 1, 2 and 3 of the Sewers of London history, along with a link to the Thomas Crapper Page.