Three presidents of the United States elected in the 1840s — William Henry Harrison, James K. Polk and Zachary Taylor — all died in office or shortly after leaving office. Harrison died on his 32nd day as president, serving the shortest tenure in American history. Whether you're a conspiracy theorist or not, it's a fishy pattern.

Now modern forensic analysis may have uncovered the common link in these suspicious deaths. It turns out, it may have been the White House drinking water, reports Business Insider.

Officially, all three died of common ailments: Harrison, of pneumonia, and Polk and Taylor died of symptoms related to gastroenteritis. But a recent reanalysis of Harrison's death suggests a different cause of death, one that establishes a more telling pattern.

The reanalysis, which included a reexamination of the physician's journal that declared Harrison's death, found startling inconsistencies. While he did experience a fever and have trouble breathing — symptoms of pneumonia — his most debilitating conditions were gastrointestinal. In fact, the physician who wrote the report expressed some doubt about his own original diagnosis. If true, this would seem to indicate that all the presidents living in the White House at the time could have died of complications from stomach bugs.

What could have caused this? Well, urban hygiene was hardly exemplar in the 1840s, and Washington, D.C., was certainly not exempt. Researchers looked at historical records to see exactly where the White House got its drinking water from at the time. Sure enough, it came from a spring that was downstream from a sewage dump just seven blocks away. In other words, residents of the White House were drinking unclean water.

This dump would have been a veritable breeding ground for the salmonella bacteria that cause gastroenteritis. So it would seem that unsanitary sewage conditions may have shortened the lives, and the tenures, of several presidents. It's not exactly the legacy any president would want to leave.

This scourge did not come to an end until the latter half of the 19th century, during a period often referred to as The Great Sanitary Awakening, when cities around Europe and the U.S. finally began to associate uncleanliness with disease, revolutionizing our sanitation systems.