Bazalgette's London sewers

London's old rivers, among them the Fleet and the Tyburn, had become open sewers, and most of the city's human waste ended up in the Thames, which was also a source of water for drinking and washing. The river had in effect become the largest open sewer in London. Cholera struck the city in 1848 to 1849 and again in 1853 to 1854.

In the summer of 1858 the Great Stink settled over London. The smell invaded the Houses of Parliament on the riverbank, and members rushed through a bill that provided the money for a new sewer system. The work went to Joseph Bazalgette (1819 to 1891), chief engineer of the Metropolitan Board of Works.

Bazalgette's plan gathered waste through about 1,100 miles of drains under the streets and fed it into 82 miles of new brick-lined main sewers. Pumping stations at Deptford, Crossness and Abbey Mills moved it on, and it was released into the lower reaches of the Thames east of the city. He insisted on wide, egg-shaped tunnels with brick walls, and the whole project used 318 million bricks. The system was officially opened in 1865, though the work was not finished until 1875.

Cholera returned in 1866, the year after the opening, in London's last epidemic of the disease. Its victims were almost all in parts of East London not yet connected to the new sewers. When the cholera pandemic that began in 1881 reached Europe, London avoided an outbreak, which a 2013 review of cholera history puts down largely to the finished sewer network. Most of Bazalgette's system still carries London's sewage.