TIL as many as three US Presidents, and also Abraham Lincoln's son, may have died as a result of a contaminated water supply to the White House. Until 1850 there was no sewage system and a field of human excrement called "night soil" flowed freely into the water supply.

SOURCE: https://www.saturdayeveningpost.com/2019/04/killer-in-the-white-house/

Summary

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For over twenty years a silent killer stalked the White House. Was this killer responsible for the death of three presidents?

As said here by Chris Wakefield

Chris Wakefield