London, beginning of the 19th century. Industrial revolution, massive population growth. First flushing toilets appear. City council is no longer capable of maintaining the numerous cesspools in the city and takes the decision to stop maintaining them.
In 1815, human waste from more than 200,000 cesspools is washed away into the river Thames, the source of drinking water. Consequently, London starts dying of cholera. Later, in 1858, during a very hot summer, all London stinks. Big time. This time is known as The Great Stink.
Whoever could, left the capital. Life for the rest was tought. People died on the streets, hospitals were over capacity.