You Won’t Believe How Often You Should Be Replacing Your Kitchen Sponge

August  3, 2017

If you’ve been mulling over whether or not it’s time to buy a dishwasher, here’s the information that could put you over the edge: there are 54 billion bacterial cells on a single cubic centimeter of the average kitchen sponge.

You might already know that it’s your kitchen, not your bathroom, that has the most microbial activity, and that’s indeed because of your sponge—"the biggest reservoirs of active bacteria in the whole house.” But did you know that cleaning your sponge only makes things worse?

In a recent study published in the journal Scientific Reports, researchers in Germany found that used kitchen sponges were home to dozens of bacterial microorganisms (the researchers charted just the top 20 bacteria), and out of the top 10 most abundant bacteria, five were closely related to those classified as RG2, microbes associated with preventable human illnesses including food poisoning. The testing size was relatively small (14 sponges, separated by top and bottom into 28 samples), but the 10 most common bacteria were “quite ubiquitous,” the study notes.

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What’s more, the samples taken from homes where they had been “regularly cleaned,” according to their owners, were even worse. In those sponges, two of the 10 most common RG2 bacteria, Chryseobacterium hominis and Moraxella osloensis, were found in “significantly greater proportions.”

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Top Comment:
“Nope. ”
— Allison C.

“From a long-term perspective,” the researchers wrote, “sponge sanitation methods appear not sufficient to effectively reduce the bacterial load in kitchen sponges and might even increase the shares of RG2-related bacteria.”

And because kitchen sponges typically get used for multiple tasks (not just cleaning dishes, but wiping countertops and any number of surfaces), our sponges aren’t just a “reservoir of microorganisms,” the team writes, “but also as disseminators over domestic surfaces, which can lead to cross–contamination of hands and food, which is considered a main cause of foodborne disease outbreaks.” In other words, your sponge is really good at spreading bacteria all over your kitchen.

So what’s a conscientious (and now completely grossed-out) household to do? Well, you’ll be happy, and not that surprised, to learn that “notably, no bacteria could be detected in a collection of newly bought, i.e. unused kitchen sponges.” Since it’s run-of-the-mill kitchen activities that bring these bacterial colonies to life, the researchers suggest that we replace our sponges weekly.

Though the team notes that more work needs to be done to measure the actual pathogenicity of the used kitchen sponge—that is, how are these sponges actually making us sick?— I feel comfortable saying that we should all just start fresh with a new sponge today, and start buying them in bulk.

If you want to get a much closer look at what’s living in your kitchen sponge, read the full study here.

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Karen Lo

Written by: Karen Lo

lunch lady


witloof April 7, 2018
I haven't read the comments here so I don't know how much I'm repeating what has already been said, but I keep my sponges for months and I never, ever get sick from my own cooking. Was this study funded by a sponge company? Articles like this scare people about things they shouldn't worry about {if you stop to think about it, how many times have you gotten food poisoning from your own cooking? I'm sixty years old, cook for myself multiple times every day, and the answer is NEVER} and distract us from what's really important.

Food52 editors, please stay away from publishing articles like this one.
sharon November 12, 2019
Just because you haven’t gotten sick from your cooking, doesn’t mean you haven’t gotten sick from other things that your sponge has come in contact with. Stay well.
Barbara P. April 5, 2018
Honestly, do you think you have EVER got sick because you used a 'dirty' sponge?? I haven't, and I do not change mine every week. Just think about all the plastic waste we are creating if we did. Be a bit sensible. And research also shows that exposure to bacteria strengthens your immune system. Or, in other words, children who are never exposed to germs develop more allergies and diseases than those that got a healthy dose of microorganisms. I am a biologist, so know a bit about germs and I am telling you: relax and use your common sense!
sharon November 13, 2019
I agree about kids near to be exposed to dirt, germs, etc. That’s one reason babies and small children need to have a dog. When I had a dishwasher, I’d put my sponges in the dw regularly. Now I buy eco sponges. I also use the newest one for dishes, countertops, etc. White vinegar and Lysol go a long way to keeping them germ free., not perfect, but better than using a new one every week. The ones that are not redeemable, I use for the messier jobs. There are eco friendly sponges available so we don’t have to fill up our landfills with the “rubber” ones.
msmely August 15, 2017
Good thing I won't be eating my sponge.
Kelly August 12, 2017
I am curious why people use sponges as opposed to scrub brushes, particularly the palm sized ones which dispense soap, which is so convenient (for me anyway). Is it habit, or the desire to utilize a product which is biodegradable or more environmentally friendly?
FT August 11, 2017
Stick them in while damp and microwave for 1 minute, boil them in hot water for a few minute. That's what I do. Basic sterilization.
KiKi P. August 11, 2017
I buy sponges in bulk at Sur Le Table and often leave it in a ceramic mug (broken handle) soaking in water and bleach in the kitchen sink overnight.
I replace once every two or three weeks, just in case! Thanks for this update on dirty kitchen sponges. I use clorox household wipes for cleaning the prep area of kitchen and hands after handling uncooked meat/fish/chicken.
beezus August 11, 2017
I have a bottle of water with bleach 8/2 ratio on the counter. Soak my sponges with that every day. One sponge for the sink, the other for the counter. I feel pretty confident that my sponges are bacteria free.
rrtrino August 11, 2017
I buy sponges in bulk from Costco and change every 1st of the month. Been doing that for over 2 decades.
Julia R. August 11, 2017
We should ditch the sponge! It's just another plastic waste that threatens our ecosystem
Daniel H. August 11, 2017
Yeah I ditched my sponge and got a dishwasher, I mean I got a dog! Highly recommended and very efficient.
Yonca August 11, 2017
Do you have a suggestion what to use instead? I'm trying to ditch all plastic but just hands don't really work when washing dishes :)
Deborah August 11, 2017
I have always used dishcloths, which used to be the only way to go. Smallish (i.e. Half or quarter the size of a dish towel), cotton, often waffle weave. Keep a stack of them, throw them in the washing machine, they last a long time and are hygienic.
Yonca August 11, 2017
Perfect! Thanks so much
txgreyhound August 11, 2017
I'm with you Daniel. When in doubt have two dogs. Throw in a cat that likes to reside on the countertops for good measure.
Frances K. March 20, 2019
I use dishcloths and take out a fresh one every morning. The used ones get washed with hot water and clorox along with the other white towels. When in my motorhome, I use those little compressed sponges from Trader Joe's and take a new one once a week.
Elaine S. August 10, 2017
I put sponges in between brackets in the top rack of my dishwasher. The
combination of powerful detergents and high heat seems to get them very clean ! Elaine May
Kathleen August 10, 2017
Sponges are gross! Another landfill item as well.
Amanda T. August 10, 2017
To those who have commented that they microwave or use bleach to clean their sponges -- it doesn't work, and in can, in fact, make things worse.
Lauryn August 10, 2017
Interesting how they say "or even cook on a stovetop," but offer no data whatsoever about what was supposedly left on the sponge :) Boil them, frequently if used for raw meat; do not cross use sponges; and dry completely between use.
Daniel H. August 11, 2017
Yeah right! The NYT and the Sponge Industry are as FAKE as CNN and Shillery Clinton! You Sheeple People are incredulous!
Allison C. August 11, 2017
The NY Times?? Are you kidding me? The FAKE NEWS NYT?? Sorry, but I'll stick with WEBMD any day over this so called "news" organization!
Deborah August 11, 2017
Joking, right?
Allison C. August 12, 2017
Mary M. August 10, 2017
Are all these bacteria really making us sick? I'm not boiling my sponges. I do run them through the microwavebot only occasionally. And we're very rarely sick -- it's been years. A new one every week? I don't think so.
Eri G. August 10, 2017
My mom used to use the same sponge for everything. Dishes. Counters. Stovetop, Oven. Oven got dirty? Scrubbed it with that sponge. Spilled something on the floor? Yup - same sponge. Someone had a dirty face? Yeah - sponge or paper towels. She tossed it in the dishwasher when it "looked dirty" or didn't pass her "sniff test". She chucked it in the garbage when it started wearing out, ie, developed holes. Yes, seriously. I'm 50-something now, and no, I'm not dead yet - I don't think. Do I recommend this same regimen to others? Not really. But I do think that this article is more fear porn for the faint of heart, and folks who like their hearts to flutter every time some goofball writes a panic piece such as this to boost sales of something (sponges, in this case). Come on, peeps. Get serious!
Daniel H. August 10, 2017
I hear you Eri, we gotta stop this kind of propaganda before they try telling us we have to start flushing our toilets or take showers at least once a year!

Daniel H. August 10, 2017
Deborah August 11, 2017
I just hate when they do those scientific studies. It just makes life so darn difficult. Like global warming and stuff. There is some plan that The NY Times and Hillary Clinton, among others, have to scare us all into doing things like throwing out our all-purpose sponges and stop idly idling our cars to warm them up or cool them down or whatever. Why, people? Think about it.
txgreyhound August 11, 2017
Eri, a very famous American said "We have nothing to fear but fear itself". Stoking fear only makes you well...............more fearful.
russelllewis August 10, 2017
Is this article brought to us by the Sponge Makers Institute of America?
Weekly... really?
I alternate between time in the microwave and time resting in a bleach solution for my sponges.
I haven't died once using this method... I guess I would be the first to know. :-)
Beverly S. August 10, 2017
I'd like to think my kitchen sponge is keeping my immune system strong!
Daniel H. August 10, 2017
A dirty sponge is the kitchens probiotic!
Daniel H. August 10, 2017
If that were the case, I'd be dead by now😵! More Fear Porn for the sheeple People.
Daniel H. August 10, 2017
I refuse to eat anything in my kitchen, without having a hazmat team there inspecting my sponges for bacteria! 😂
Lauryn August 10, 2017
What on earth were the sponge sanitation methods" considered? Boiling will kill anything concerning, and somehow you've left out basic common sense methods and only speak about terrible sponge habits. Dry all sponges completely after use, and keep two out if necessary for this to alternate; if you use a sponge for anything with raw meat, or the bottom of the sink, DO NOT use that sponge for kitchen counters or elsewhere; and boil sponges much more frequently if cleaning raw meat items. After boiling for 10+ minutes (really the only requirement is non-plastic sponges, and to keep an eye on the water level that it doesn't boil off), cool, or pour most off into sink if desired, cover with cold water to cool faster, and when cool enough to handle, squeeze out and let dry completely. Sponges can last until they literally wear out with this care.
alex G. August 10, 2017
My grandparents were raised on small villages in Greece in the early 1900s. They lived well into their hundreds and never worried about this. Research has shown that all our attempts to kill through ant microbia, antibiotic, vaccines is creating more virulent strains of microbes, bacteria, and viruses. Maybe we should stop trying to kill everything and stop poisoning ourselves so our immune systems stand a chance
Janice D. August 10, 2017
It was my understanding that microwaving sponges for two minutes kills bacteria, including illness-causing bacteria, like E. coli. See