Joseph Bazalgette

London in the 1850s emptied its cesspits into the Thames and drank from it. Cholera killed tens of thousands in successive epidemics, blamed on bad air rather than water. What finally forced action was the smell: in the hot summer of 1858 the river stank so badly that Parliament, sitting beside it, hung curtains soaked in chloride of lime and then voted the money in eighteen days.

Bazalgette laid twenty-two thousand kilometres of street sewers feeding a hundred and thirty kilometres of main interceptors, running along and under new embankments that also narrowed the river and carried a railway. Calculating the pipe diameter London would need, he doubled it, saying that this was the sort of thing you only do once and unforeseen things always happen. The system carried the city through a population several times larger than he designed for and is still the core of London's drainage. Cholera did not return after 1866, and that outbreak occurred in the one district not yet connected. He was knighted, and is buried at Wimbledon; his memorial on the Victoria Embankment carries two words about the river.