How the London Sewer System Helped Science Discover Germs

In 1854, Broad Street residents began experiencing terrible bowel pain and diarrhea. Some of them were dead within hours of the symptoms appearing. London was in the midst of an outbreak, and there was only so much time the city could waste trying to diagnose the problem.

During the Industrial Revolution, London was a filthy place. Sewer gases frequently vented from the tunnels below ground, and there were very few sources of clean water. Those who owned homes would haul their human waste to the Thames for dumping.

Today’s Londoners would be appalled to find out that this was happening in their city, but it was standard practice back then.

Enter John Snow, a physician who had published a paper theorizing how Cholera was transmitted in 1849. The disease had already wreaked havoc among humanity, and physicians were eager to crack the case of what caused it and how to treat it.

Snow drew a map of London during the broad Street outbreak, dotting every cholera case he found to create a heat map of sorts. He analyzed various statistics in the area and came to the conclusion that the Broad Street water pump was the source of the problem.

The local council was so convinced that they removed the handle and disabled the pump. John Snow had correctly diagnosed the source of cholera, potentially opening the door for an immediate breakthrough in city planning. The problem was his ideas were discarded almost as quickly as the outbreak subsided. They refused to believe that fecal matter had leaked into the water supply and replaced the pipe because in their words, the thought was “too depressing” to accept.

Thankfully, London has evolved a great deal since those days.