Your can opener holds more germs than you think: here’s the 10-second cleaning step almost everyone skips
Think about the last can you opened. Maybe it was black beans for taco night, tuna for a sandwich, or soup after a long day. You cranked the opener around, popped the lid, dumped the food out, and tossed the opener back in the drawer.
Now think about the last time you actually cleaned that opener. Not rinsed. Cleaned.
For most people, the answer is “I can’t remember.” And that’s the whole problem in one sentence.
The kitchen tool you use to open food, the one whose blade touches your beans and your tuna and your soup, is one of the dirtiest things in your entire kitchen. It’s not close, either. When scientists actually tested this in real homes, the can opener ended up in a spot most people would never guess.
What scientists found on the can opener
In 2013, NSF International (a public health group that tests and approves kitchen products for safety around the world) ran a household germ study. Their scientists went into 20 real family kitchens and swabbed 14 common items. Then they tested every swab for four types of germs: E. coli, Salmonella, yeast, and mold.
The can opener made the top six dirtiest items on the list.
According to NSF, the can opener in the test kitchens came back positive for Salmonella, E. coli, yeast, and mold. Not one or two of them. All four.
Even worse, when NSF asked volunteers ahead of time to guess which items would be dirtiest, most of them named the can opener. They knew, on some level, that it was gross. They just weren’t actually cleaning it.
That’s the weird part the study caught: people knew the can opener was probably gross, and still weren’t doing what would actually clean it.
Why rinsing doesn’t do the job
Here’s where most people go wrong, and it’s easy to see why. After opening a can, you take the opener over to the sink, run some hot water over the wheel, and stick it back in the drawer. It looks clean. Nothing visible is on it. Job done, right?
Not quite. Water alone doesn’t do what you think it does.
Think about what actually gets on that cutting wheel. Tuna oil. Tomato juice. Coconut milk. Bean liquid. Chicken broth. These aren’t just watery. They’re a mix of fat, protein, and starch that dries into a thin, sticky film on the metal.
That film is exactly the kind of surface germs love to grow on. And here’s the part that trips people up: water can’t wash off grease on its own. You can rinse a greasy plate for a full minute and it’ll still feel slick. Rinse a can opener for 10 seconds and the food gunk is still there, just wet now.
The CDC says it plainly on their cleaning guidance page: to actually get germs off a surface, you need soap and scrubbing. The soap grabs the greasy stuff and washes it away. The scrubbing knocks it loose. Water alone just pushes things around.
So if you’re one of the many people who rinses and calls it done, your can opener isn’t clean. It’s rinsed. Those are two different things.
The one part that gets missed
There’s also a specific spot almost everyone misses even when they do try to wash it, and it’s the exact part that touches your food.
Look at your can opener. See that little cutting wheel? Now look at the tiny toothed gear right next to it (the one that grips the rim of the can and pulls it around). Jennifer Pallian, a registered dietitian with 15 years in food science who works as the food scientist for Chatelaine magazine, points out that the cutting wheel and the toothed gear are exactly where the food gunk collects, and a sponge can’t reach either one.
“Kitchen tools that touch food directly are the dirtiest, and the can opener is a prime example,” Pallian says. If you can see any gunk, any dried liquid, or any rust on the wheel, whatever is on there is going to end up on your food the next time you crank the handle.
So even if you’re one of the people who does grab dish soap sometimes, if you’re using a regular sponge, you’re wiping the outside of the opener and missing the cutting wheel and the little gear next to it, which are the only two parts that ever touch your food.
The 10-second step almost everyone skips
Ready for the fix? It’s boring. That’s the point.
Here’s the 10-second step almost everyone skips:
- Squirt a drop of dish soap right on the cutting wheel and the toothed gear.
- Grab an old toothbrush (or a small dish brush) and scrub both parts for about 10 seconds. Get in between the teeth on the gear. This is the spot a sponge can’t reach, and it’s the whole reason your can opener stays dirty.
- Rinse under hot water.
- Dry it right away with a towel. Don’t let it air-dry sitting in a puddle. That’s what causes rust.
That’s it. The missing step is soap plus a toothbrush on the wheel and the gear. Ten seconds of actual scrubbing, and the food gunk is gone. NSF’s guidance says the same thing: “wash the can opener in hot soapy water, rinsing thoroughly with clean tap water before air drying after each use,” with special attention to the area around the cutting blades.
If your can opener says dishwasher-safe on it, even better. Just toss it on the top rack after each use and let the dishwasher do the whole thing. Both NSF and Pallian recommend this option if the opener can handle it. The catch: some can openers with carbon steel blades can rust in the dishwasher, so check yours first. If in doubt, stick with the soap-and-toothbrush method.
When it’s time to replace it
One more thing worth knowing. Even a well-cleaned can opener doesn’t last forever. Pallian says if your opener has rust that keeps coming back within days of cleaning, a dull blade that leaves jagged lids, or gunk that won’t scrub off anymore, it’s done. At that point, no amount of washing gets it truly clean. A basic new one costs a couple of dollars (a few euros, or a few pounds). Not a big deal.
Sources: (1) NSF International, “Clean the Germiest Kitchen Items”; (2) 2013 NSF International Household Germ Study (PDF); (3) Jennifer Pallian, RD, quoted via Simply Recipes, “You Aren’t Cleaning Your Can Opener Enough”; (4) CDC, “Cleaning and Disinfecting”; (5) Jennifer Pallian professional profile, Foodess.