July 7, 2025, 12:52 pm | Read time: 3 minutes
You’ve likely heard of the so-called “3-second rule.” But is it a myth, or does it have a scientific basis? And does it apply within your own home? myHOMEBOOK consulted an expert to find out.
The 3-second rule is a common belief that suggests food that hasn’t been on the floor for more than three seconds is still edible. Allegedly, harmful bacteria don’t settle in such a short time. A microbiologist clarifies the rule—and explains whether it applies to households, if it’s valid at all.
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Study Has Already Examined the 3-Second Rule
myHOMEBOOK consulted Prof. Dr. Markus Egert from Furtwangen University to get his take on the 3-second rule. The microbiologist referred to a study that has already addressed this question. However, it focused not on three but on five seconds.
The study was published in 2016 by Robyn C. Miranda and Donald W. Schaffner at Rutgers University (New Jersey, USA) and appeared in the journal “Applied and Environmental Microbiology.” The aim was to scientifically examine the so-called “5-second rule.” Researchers contaminated four types of surfaces (stainless steel, ceramic tiles, wood, and carpet) with the bacterium Enterobacter aerogenes. They then studied how much various foods, such as watermelon and bread, were contaminated at different contact times (<1 second to 5 minutes).
The results show: Bacterial transfer occurs within fractions of a second. Moist foods like watermelon and smooth surfaces like tiles have the highest transfer rates. Longer contact times significantly increase the contamination rate, clearly disproving the 5-second rule—and thus the 3-second rule.
What the Microbiologist Says About the 3-Second Rule
Egert confirms the study’s findings. “If food stays on the floor for a long time, more microbes can adhere to it than if it stays for a very short time.” He adds, “Microbes can stick to fallen food even after one second, and the type of food and floor, as well as its cleanliness, play a bigger role than time.”
About the Person: Prof. Dr. rer. nat. Markus Egert is a renowned microbiologist and hygiene expert at Furtwangen University (HFU). Since 2011, he has been teaching and researching at HFU, focusing on applied microbiology, molecular microbiology, and hygiene in households and industry.
Moist foods and those with large surfaces—such as a piece of melon or sausage—tend to pick up more germs quickly than dry ones, like bread. “This is especially problematic on unhygienic surfaces, where pathogens also lurk,” Egert explains. He cites examples like a used sink or the bathroom floor—places found in one’s own home.
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Should You Still Eat Food That Has Fallen?
Should you immediately dispose of food that has landed on the floor? It depends, Egert answers. “A dry gummy bear that falls on grass or a clean tile floor at home can still be eaten after ten seconds.” So there’s no need to worry here. But: “A piece of gum that falls out of your mouth in a public restroom, I wouldn’t put back in my mouth even after one second.”