The Aldgate Death Pump.
Since the 16th century, the pump stood in London and was known for its mineral-rich spring water. This continued until 1876, when calcium from human bones was found in water samples.
As it turned out, the spring had washed away nearby cemeteries and the water literally contained human remains.
While this was being investigated, people continued to drink water and an epidemic began - hundreds of people died after drinking tainted water.
