Delaware Division of Libraries Blog
Division of Libraries' Blog

Division of Libraries

Facebook  Twitter  Pinterest  Flickr  Google+  YouTube  Instagram


Q: Is the 5-second rule true?

Written on: July 10th, 2009 by: in Q & A's

bacteriaThe 5-second rule states dropped food that spends less than 5 seconds on the floor  is safe to eat.

The short answer is no, it is not true.  In 2005, the Discovery Channel’s Dr. Know went to scientists at the University of Maryland to test the rule.  Moist foods, like lunchmeat, picked up germs faster than dry foods, like crackers, but all the food still had germs.  The scientists found “Food that has been on the floor for five seconds or less is no safer to eat than food that has been on the floor for a long time.”

In 2003, a high-school intern at the University of Illinois conducted an experiment on the 5-second rule (with graduate-level supervision).  She found “…if you drop your food on a floor that does contain microorganisms, the food can be contaminated in 5 seconds or less. ”

At Clemson University, food scientists discovered “In the case of the five-second-rule…bacteria was transferred from tabletops and floors to the food within five seconds.”  The Discovery Channel’s MythBusters declared this myth “busted.”  And, Nemours reminds us that “A clean-looking floor isn’t necessarily clean. A shiny linoleum floor is probably cleaner than a 1970s-era carpet. But even clean, dry floors can harbor bacteria. Newly washed floors are only as clean as the tools used to wash them.”

Thanks for using Ask a Librarian Delaware!  Have a question?  Ask us!