If you think your cell phone is dirtier than your toilet, the kitchen sponge has that one beat. The truth of the matter is, that pretty yellow, blue, or pink sponge is holding approximately 45 billion bacteria per cubic centimeter. With all of that, you’re probably wondering how to kill bacteria in a kitchen sponge?
Did you know a household kitchen sponge holds 200,000 times more germs than your entire house? That’s crazy!
To prevent cross-contamination, each sponge should have its specific job and you shouldn’t intermingle them with other duties.
Let’s say you have a sponge you use for cleaning off the counter; you wouldn’t want to use that same sponge to clean the sidewalls of your refrigerator. If you use a sponge to clean the kitchen dishes, you wouldn’t want to use the same sponge to clean the dog or cat bowl.
If you’re going to use a kitchen sponge, use it specifically for one purpose only.
The not so secret things people do with their kitchen sponges and things you SHOULD NEVER do
Wiping meat juice off a plate, then using that same sponge to clean dishes. Just because you’re using soap, it doesn’t necessarily mean your sponge won’t be harboring any harmful bacteria. If you’re gonna do this, use a paper towel. The same thing goes for cutting boards.
Scrubbing fruit and vegetable skin. You should never use a sponge to clean off your fruits and vegetables. If you want to rid them of pesticides or germs from other grocery shoppers, you’ll want to invest in a vegetable scrubber. They’re not that expensive and you can find them at your local dollar or big box store
Wiping your hands on a dishtowel after using a kitchen sponge. Do you honestly think the fibers of the dishtowel are going to repeal the bacteria? Nope, heck I’m sure a few of the bacteria spores are using the fibers of the dishtowel as a hammock.
By doing this you’ll stand a much greater risk at cross-contamination, which can promote a foodborne illness.
Kitchen sponge maintenance and care
How to store your used sponge
Is it sitting on the back edge of the sink? How about in an old margarine tube under the sink? Is it just laying in the sink?
The best way to store a sponge is by using a sponge drying rack, or someplace where air can circulate through the fibers.
Before placing it on a drying rack you’ll want to:
- Wash it with soap and rinse it thoroughly after each use.
- Ring it out as best as you can to remove all of the excess water. The drier it is the better.
Replace your kitchen sponge frequently
The good thing about sponges is, they’re pretty darn cheap, so it shouldn’t hurt your wallet to throw them out on a bi-weekly to monthly basis. If you can’t part with throwing them out that frequently, then your best bet would be to disinfect your sponge.
If you use your kitchen sponge daily, you should change it out every week or so. Even if you’re not using it that often you still need to replace it at a minimum of once a month. Sure, that may seem like you’re throwing money down the drain, but the truth of the matter is, it’s still breeding bacteria.
How do you know when it’s time to throw it out?
When your sponge starts to smell like rotten blue cheese mixed with curdled milk, or just dirty smelling, it’s time to go.
If you still want to keep it, you may want to put it in rotation to clean the inside of your toilet bowl or to clean the insides of the trash can or recycle buckets.
To be sure you don’t get your new toilet cleaning sponges confused with your kitchen, you’ll want to cut off a corner of the old sponge. Doing this will avoid any confusion you might have, especially if both sponges are the same color.
Family members with health conditions
If you or your family member either has an immunosuppressed illness or cancer, you should never allow a sponge into your home.
Due to the number of bacteria the sponge harbors, and regardless if you disinfect the sponge, you may not have disinfected it thoroughly enough. There is a very strong possibility you can transfer some of the sponges’ bacteria to your family member.
If you still want to keep a sponge in your kitchen, the best bet would be to always wash your hands with hot soapy water after using the sponge.
The proper ways to disinfect a kitchen sponge
Microwave disinfection
According to the USDA, microwaving sponges kill 99.9999% of bacteria, while dishwashing kills 99.99998%.
Hey, that’s great but what about that other teeny-tiny percentage it doesn’t kill?
In a 2017 published article in Scientific Reports it explains your sponge contains a little ecosystem. They state every home harbors different bacteria – which is understandable – but they did find a great deal of salmonella and staphylococcus in a kitchen sponge.
Although the microwave will kill most of the bacteria, it’s not going to kill all of it. due to the different materials that make up each type of sponge
Some sponges are made up of a synthetic metallic property that can catch on fire in the microwave. Another important factor is, if your sponge isn’t thoroughly wet, it can cause a fire, regardless if it has synthetic metallic properties in it.
Before using your microwave to disinfect a kitchen sponge, it’s imperative to make sure your sponge is wet enough to cause enough steam to penetrate all of the sponge fibers.

How to disinfect a kitchen sponge
Place the wet sponge on a paper plate. It must remain in the microwave for no less than 2 minutes; however, due to the variance in wattage of microwaves, 2 minutes may not be long enough.
After you use your microwave to disinfect the sponge, make sure you disinfect the microwave immediately after.
Why do you ask? You just put a gross stinky bacteria-laden sponge that’s probably filled with fecal bacteria, parasites, and other types of bacteria in the same place you’re planning on heating your Hot Pocket.
Dishwasher disinfection
Putting your sponge in the dishwasher is a very easy and effective disinfection method. Place your freshly rinsed kitchen sponge on the top rack nestled between two slats. You can also place your sponge in the utensil holder; however, more than likely you’ll need to fold it a bit for it to fit.
While in theory, the utensil holder sounds like the best option, there’s a slight possibility the hot water and detergent won’t be able to reach the folded part of the sponge. Although sponges absorb a lot of water, the absorption level only goes so far.
How to disinfect a sponge in the dishwasher
- Use the hottest and longest setting on your dishwasher
- Make sure you use the heat setting when drying. Let it complete the full drying cycle before removing your kitchen sponge.
Bleach disinfection
This is the third and final way to disinfect your kitchen sponge.
Make a bleach bath
- Use 1/2 teaspoon of bleach to a quart of warm water.
- Let the sponge sit for one minute.
Studies have reported you should use a minimum of 8.25% sodium hypochlorite. The only issue with this is, most household bleach ranges anywhere between 5.25% to 6.0% sodium hypochlorite.
I have both Great Value and Dollar General bleach in my home. Great Value is listed as 6.0% sodium hypochlorite and 94% other. I’d love to know what the other 94% is. Now, on the other hand, Dollar General bleach doesn’t list the active ingredients on the packaging at all.
Does that mean you can’t use it? Of course not. Use the bleach you have on hand, but to be on the safe side, let the sponge soak for 3 minutes instead of 2.
Your Turn
Do you disinfect your kitchen sponges, throw them out, or don’t even use them? Share in a comment below!
Until we meet again,
Stacey
Scientific Reference: Microbiome Analysis and Confocal Microscopy Of Used Kitchen Sponges Reveal Massive Colonization By Acinetobacter , Moraxella and Chryseobacterium Species. Massimiliano Cardinale-Dominik Kaiser-Tillmann Lueders-Sylvia Schnell-Markus Egert – https://www.nature.com/articles/s41598-017-06055-9
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