The drinks you get from soda fountain machines in restaurants and fast food outlets could contain fecal bacteria, suggests a new study.

U.S. researchers found that nearly half of all sodas dispensed from 30 machines in the Roanoke Valley in Virginia had coliform bacteria, which indicates the possibility of fecal contamination, ABC News reported.

"About 70 percent of the beverages had bacteria and 48 percent of them had coliform bacteria," said study co-author Renee D. Godard, a professor of biology at Hollins University.

The study appears in the January print issue of the International Journal of Food Microbiology.

Godard said it's not clear where the bacteria come from, but noted that just one contamination of the soda fountain nozzle could enable bacteria to grow into the plastic tubing and start colonizing within the machine, ABC News reported.

The problem could be prevented if soda fountains were rinsed out more often.