Backyard chicken farming has exploded in the past decade, with flocks cropping up everywhere from the hipster heavy neighborhoods of Brooklyn, New York to beach towns like Malibu, California. But while more people than ever are walking out their back door to grab some fresh eggs from the nest for breakfast or walking next door to ask their neighbor if they can hit the coop for their omelet fixings, they’re also being faced with a question rarely asked of the store-bought variety: Should I wash this egg before I eat it? It did just come out of a chicken’s behind, after all. 

It’s a question Lisa Steele, author of the book Fresh Eggs Daily and founder of the popular backyard poultry site of the same name, gets fairly frequently. Her answer is always the same: “[Washing] is the last thing you want to do.”

The laying process coats a chicken’s eggs with something called a bloom or a cuticle, Steele explains, an invisible layer meant to protect the porous shell from bacteria. “Mother nature decided to seal off the egg,” Steele says. “If you wash that off, you make the egg more prone to bacteria.” 

The eggs you find in the grocery store must be cleaned by chicken farmers under US federal law, or they can’t be sold. Those washing procedures are strictly regulated, with farmers barred from allowing eggs to soak in water and even the amount of iron in water used during the cleaning process regulated. 

But this is a uniquely American process. Washing commercial eggs is largely discouraged in Europe, where marketing standards for eggs include a warning that, “such practices can cause damage to the egg shell, which is an effective barrier to bacterial ingress with an array of antimicrobial properties” and note the process could “favor trans-shell contamination with bacteria and moisture loss and thereby increase the risk to consumers.”

This is especially true if you’re washing the egg at the wrong temperature, Steele says. Water should be 20 degrees warmer than the egg itself to prevent it from soaking through the thin shell via osmosis, and getting that temperature wrong could create a food hazard.    

Even the United States Department of Agriculture outright recommends against egg washing for consumers on its website, noting that doing so can actually increase contamination, with the water forcing bacteria through the shell and into your future frittata fixings.

But what about poop on an egg? Still feeling a little grossed out over the idea of keeping something in your fridge that could be covered in chicken shit? 

First, an anatomy lesson: Hens lay eggs from a vent underneath all those feathers. It’s the same one that expels urine and feces, but you’ll be relieved to know that Mother Nature thought of your ick factor. That vent has a membrane that turns inside out during the laying process to protect the egg from the chicken’s other excretions. So poop doesn’t actually touch the egg. 

What’s more, Lissa Lucas, co-author of My Pet Chicken Handbook, says good coop management will keep the laying environment clean and free of feces and mud. “If you're someone who has a small flock in your backyard and you're managing your coop well, you probably will not have any eggs that are actually ‘dirty,’” Lucas says. 

That said, every egg does need to be checked out before it’s brought inside. “Life being what it is, sometimes you have a hen walk through the mud, possibly poopy mud if your birds are closely confined, and track it into the nest and onto egg,” Lucas admits. An egg that dirty represents a hazard even if it’s used fairly quickly, because cracking introduces the bacteria into the yolk, which can infect your omelet. 

When that happens, Lucas recommends the “better safe than sorry” method: Throwing the whole thing out rather than trying to save it with a bath. “Dirty eggs occur seldom enough in well-cared for backyard flocks that many people just toss a dirty egg out, which is what I prefer to do rather than washing it,” she says. The same goes for eggs with cracks, which are more susceptible to bacteria.

If you do clean an egg, the experts recommend immediate refrigeration as the cold will help keep bacteria at bay. If kept out at room temperature, unwashed eggs will remain good for at least two weeks. Unwashed and refrigerated eggs typically last much longer—as much as three months.

If you insist on cleaning an egg, Steele recommends using a fingernail to remove small spots of dirt or purchasing one of the egg sanitizing wipes that are on the market. “You don’t need vinegar; you don’t need bleach,” she says, “really you can just use your fingernail.”