Soda fountains contain fecal bacteria.

Even more disgusting than that, some soda fountains even contain Mountain Dew. From CNN:

It fizzes. It quenches. And it could also contain fecal bacteria.

Nearly half of the 90 beverages from soda fountain machines in one area in Virginia tested positive for coliform bacteria -- which could indicate possible fecal contamination, according to a study published in the January issue of International Journal of Food Microbiology.

Researchers also detected antibiotic-resistant microbes and E.coli in the soda samples.

"Certainly we come in contact with bacteria all the time," Renee Godard, lead author of the study and professor of biology and environmental studies at Hollins University, a private liberal arts college in Roanoke, Virginia. "It's simply that some bacteria may potentially cause some disease or gastrointestinal distress. One thing we hesitate with is that people get afraid of bacteria. Many of them are benign or helpful, but certainly, I don't want E.coli in my beverage."

The U.S. Environmental Protection Agency's drinking-water regulations require that all samples test negative for E.coli.

Many of the soda beverages from the dispensers fell below U.S. drinking-water standards, according to the findings.

"The large number of beverages and soda fountain machines containing E. coli is still of considerable concern... and suggests that more pathogenic strains of bacteria could persist and thrive in soda fountain machines if introduced," the authors wrote.