Few topics in the culinary world spark as much passive-aggressive kitchen tension as basic food safety habits. A perfect example of this is captured in the viral pic, which reads:
"Why don't people wash eggs before cooking them? This is like the third time I've seen my sister-in-law use eggs without washing them. I know it's none of my business, but doesn't everyone wash eggs?"
If you’ve ever found yourself asking this exact same question while watching a relative crack eggs straight out of the carton, you might be surprised to learn that science, food safety experts, and federal regulations are entirely on your sister-in-law's side.
While washing produce or rinsing hands before cooking is common sense, giving your grocery store eggs a scrub before breaking them open is not only unnecessary—it can actually make your food dangerous to eat.
The Science Behind the Shell: What Is the "Bloom"?
To understand why washing eggs is a bad idea, you have to look at how nature protects them. When a hen lays an egg, a natural, microscopic protective coating called the bloom (or cuticle) is deposited on the outside of the shell.
Because eggshells are inherently porous—containing thousands of tiny holes—this bloom acts as a crucial safety barrier.It seals the pores, keeping oxygen and moisture inside while preventing environmental bacteria, such as Salmonella, from penetrating the shell and contaminating the egg inside.
The Commercial Process (Why Store-Bought Eggs Are Different)
Depending on where you live in the world, the rules for handling eggs change dramatically:
In the United States, Canada, and Japan: Federal regulations require commercial egg producers to thoroughly wash and sanitize eggs before they ever reach grocery shelves to eliminate any surface bacteria. Because this rigorous washing process strips away the natural bloom, producers spray the eggs with a light layer of edible mineral oil to replicate that barrier. Washing them again at home ruins this artificial seal. Because they have been washed, these eggs must be kept refrigerated.
In Europe and the UK: Commercial egg washing is actually prohibited for high-grade eggs. European food safety authorities prefer to keep the natural bloom intact, meaning eggs retain their natural defense system and can safely sit on unrefrigerated supermarket shelves for weeks.
No matter which system your country uses, running a grocery store egg under the kitchen tap does more harm than good.
The Dangerous "Vacuum Effect"
The biggest risk of washing eggs at home comes down to physics. If you rinse a cold egg under tap water—especially cool or running water—the temperature difference causes the contents inside the egg to contract slightly.
This contraction creates a microscopic vacuum effect, actively pulling the water, along with any lingering bacteria or dirty residues on the surface of the shell, straight through the pores and into the part of the egg you are about to eat.
Furthermore, splashing water around the sink while trying to wash an egg increases the risk of cross-contaminating your countertops, sponges, and nearby utensils with surface bacteria.
What About Farm-Fresh Eggs?
If you are harvesting eggs directly from a backyard coop or buying them unwashed from a local farmer, they may occasionally have a little dirt or debris on them. In this scenario, experts still recommend avoiding a wet wash if possible. Instead, use a dry, slightly rough cloth or a piece of fine-grit sandpaper to gently brush away any debris, preserving the bloom so the eggs remain shelf-stable at room temperature.
If you absolutely must wash a heavily soiled farm egg, use warm water that is significantly hotter than the egg itself (which forces the contents to expand and push bacteria out rather than pulling it in), dry it immediately, and put it straight into the refrigerator.
The next time you see someone cracking eggs straight from the carton without a rinse, hold your tongue! As the text hilariously highlights, it really is best to mind your business on this one. Your sister-in-law isn't being messy—she’s just practicing excellent food safety.
Save yourself the extra step, trust the natural barrier of the shell, and always remember to wash your hands after handling the shells instead!