Throw Out Your Kitchen Sponge ASAP—Yes, Really

Cleaning it won't help.

March  4, 2022
Photo by Julia Gartland

If you’ve been mulling over whether or not it’s time to buy or replace 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. They are breeding grounds for all types of germs and bacteria. Dishwashers are naturally a much more sanitary way to wash and disinfect dishes, utensils, glasses, and some cookware (but don’t you dare put your cast iron in there).

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? Sticking your sponge in the dishwasher or boiling water to disinfect is a no-go, and leaving it to sit in soapy water at the bottom of your sink is also a bad idea. Yes, really.

In a 2017 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.

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.”

“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 scrubbing any number of sticky 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. That’s right: ditch your sponges every single week. If you’re unsure whether it’s a good time to get rid of your sponge, give it a sniff. If it smells off or downright wretched, obviously toss it.

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.

Our Favorite Eco-Friendly Sponges

To eliminate so much waste, choose plant-based sponges that are entirely biodegradable to reduce waste and one’s carbon footprint. Our own Five Two Compostable Sponge Cleaning Cloths are an all-natural swap for paper towels or sponges, perfect for cleaning up countertop messes. They’re made from plant fibers and water-based ink, and are guaranteed to decompose in a home compost within six weeks.

Grove Collaborative also sells some of our favorite sponges made from plant-based, recycled materials: walnut shells, plant cellulose, and recycled PET (a type of plastic). If you’re shopping at a regular grocery store, keep an eye out for Scotch Brite Greener Clean Non-Scratch Scrub Sponges, which are made from natural plant fibers. With so many eco-friendly options, you can replace your sponge each week guilt-free.

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

This article was updated in March 2022 with even more cleaning recommendations from our editors.
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See what other Food52 readers are saying.

  • Thomas Gorman
    Thomas Gorman
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Karen Lo

Written by: Karen Lo

lunch lady


Thomas G. March 10, 2022
Handi-wipes. They rinse out cleanly and are dry in an hour after using … squeeze right out, hang it over the sink… always fresh & never a stink!✨
anne March 12, 2022
Handi wipes? To wash dishes? No Gorman, they are two thin. How many dishes do you actually wash anyway, I bet your wife is doing them.
clove March 10, 2022
What about soaking your sponge in a little soapy bleach water? This article makes it sound like we will all die from our sponges! Lol!
J March 6, 2022
I’ve just read the “study” and it’s bogus. They go on and on about bacteria found in kitchen sponges, but how long have those sponges been in a kitchen? One day? 50 days? 365 days? What? There is but one paragraph that mentions some conventional cleaning methods, such as microwave, but without either data or conclusion. The word “dishwasher” does not appear, although the author uses it. I’m pretty sure the average life of my kitchen sponges is about 6 months—never used for floors, only for dishes—and they pop into the sanitizing dishwasher every day. Voila! Clean every day. (I do make sure to squeeze out liquid and store so as to maximize air flow) Dear “scientists” : please come into my kitchen and analyze my old sponges for bacteria!
Liz S. March 7, 2022
YES!!! So many studies about anything are limited in scope, detail and correlation vs causation. The sponge topic comes up repeatedly and yet, gosh, most of us have used a kitchen sponge for years with no ill affects. Click bate Food52!! And I fell for it :(
Adamantis March 6, 2022
I grow luffa and use them for sponges in the kitchen and bath.
Jo March 6, 2022
I buy those yellow sponges from Trader Joe’s or WS when on sale. I have 7 on rotation each morning I toss the dirty one in my kitchen basket twice a week at least I wash the basket of sponges towels placemats in hot soapy oxy detergent that I rinse with the Lysol disinfectant rinse that I love. Then dry in a hot dry soon I’ll dry the sponges o out doors on my laundry rack. I’m tired of these articles I’m also in my 60s never had an issue with my sponges because I change them out frequently since Covid I use this new procedure. I’m lucky to have a washer dryer I understand it’s a luxury not everyone has.
witloof March 5, 2022
I am 64 years old andI have never ever gotten sick from using a kitchen sponge. I hate this kind of article.
witloof March 5, 2022
OMG I didn't see that this was an old article and I already commented the same thing four years ago!
Smaug March 6, 2022
Probably true, after all you most likely rinse your dishes after you wash them, but I don't see how you can really know it unless you've never been sick.
Smaug March 4, 2022
Don't have a kitchen sponge to throw out. Rags are cheaper, do a better job, and can be thrown in the wash at the end of the day; don't see any reason for kitchen sponges other than that they represent sales for someone.
marilu March 10, 2022
Smaug, I have no idea who you are but you always leave such good suggestions on so many articles and recipes I read. How do you know so much? Share me your secrets!
Smaug March 11, 2022
I don't know, old and interested in the world about me? Willing to be a pain in the posterior? And I try not to comment on the innumerable subjects that I know nothing about
marilu March 11, 2022
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.
witloof March 5, 2022
I rarely get sick. Maybe once every two or three years I get a cold.
bletch March 18, 2022
Yes, your sponge maybe going out when you're asleep and partying and who knows where they've been. And oh my oh my, maybe you were sick and asymptomatic and didn't even know it! Old sponges can cause jaywalking and if let outside on their own even contaminate your children's sandbox. It could even be worse than that. ;-)

Food52 editors, please stay away from publishing articles like this one!!!!
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?
bletch March 18, 2022
I am curious why people are curious about things like this. It's clearly genetic and entirely depends on what you ancestors did.
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.
anne March 5, 2022
That microwave thing doesn't actually work. but who cares, I've never, not once, died from using a sponge in my kitchen.
bletch March 18, 2022
It works f you leave them in there for a really, really, really long time and they start to smoke.
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.
bletch March 18, 2022
That was in 2017. And are you still alive?
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.
bletch March 18, 2022
I hope it's not the same countertop you use the sponge on. Yikes!
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
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
bletch March 18, 2022
Yes much, much worse if one ingests the bleach.
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.
bletch March 18, 2022
Oh my. How sick were you? How many of you? How long ago?
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.