London, England had a big problem in the mid-1800s. Cholera (a disease that causes an infection in the small intestine) was breaking out and spreading rapidly through poor sanitation. The cholera outbreak from 1848-49 killed approximately 54,000-62,000 in London, and the outbreak from 1853-54 killed an estimated 31,000 in the city.

Doctors at the time were operating under the “Miasma Theory”, the thought that illnesses were spread through poor quality air. From their perspective that made a lot of sense—rotten food smelled bad, and if you ate it you’d get sick—so it meant that a lot of preventative medicine was centred on cleaning up the city or appealing to a deity. Illnesses like cholera were frequently associated with being poor, impure, or lazy.

London was overcrowded and had many infrastructure problems that go along with large numbers of people. The sewers were often overworked and cesspits developed in the basements and backyards of houses, particularly in the poorer areas of the city. The government responded by dumping the waste from those cesspits into the River Thames, thereby making the river undrinkable, forcing the locals to get their water from pumps that were scattered in public squares all around the city. Despite this, some unscrupulous water pump companies continued to draw tainted water from the Thames.