How to Clean a Sponge—Because It’s Really, Really Dirty

A used sponge is one of the dirtiest things in your kitchen. Here's the best way to effectively clean a sponge.

Sponge on kitchen sinkShutterstock / Sanphoto69
Shutterstock / Sanphoto69

Sponges are a mainstay in most people’s kitchens. They make wiping down counter tops, cleaning dirty dishes, and scrubbing stubborn grease off your pans a breeze. But while they’re supposed to be a symbol of cleanliness, they’re actually one of the dirtiest things in your kitchen.

We Mean Really, Really Dirty

Sponges absorb everything—water, soap and yes, tons of bacteria. A recent study in Scientific Reports analyzed 14 sponges and found about 82 billion bacteria living in just 1 cubic inch. Some bacteria found in these sponges are also present in human and animal feces, while others can cause diseases like E.coli and salmonella. If those stats weren’t enough to make you cringe, some sources claim sponges are dirtier than your toilet seat. We’ll let that sink in.

How to Clean a Sponge

Since sponges aren’t going anywhere anytime soon, it’s important to learn how to properly clean your sponges. So how do you do it? Well, it’s complicated.

For years, most cleaning experts said the best way to do it was by throwing them in your microwave for a few seconds; however, recent reports now claim it can attract even more pathogen-related bacteria. Eek! There’s no practice that will get rid of all bacteria, but using bleach is your best bet.

Mix 3/4 cup of bleach with a gallon of water in your kitchen sink and submerge your sponge in the mixture for five minutes.

Soaking your sponge in bleach can kill 99.9% of three big strains of bacteria, plus it’s an easy way to clean your sink, too.

But the most important thing to learn is when to throw out your sponge. Depending on how frequently you use your sponge, you should replace it on a weekly basis. But if it starts to smell or is covered in food stains, err on the side of caution and kick it to the curb.

The ugly truth is that it’s virtually impossible to get rid of all bacteria once and for all. Bacteria thrives on wet, idle sponges and can grow every 20 minutes. Yuck!

If the mere thought of using a sponge makes you lose your appetite, we recommend using paper towels instead. It’s not the most eco-friendly option, but it’s significantly cleaner and will work on most food stains.

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Kelsey Mulvey
Kelsey Mulvey is a freelance writer and editor based in New York. Her hobbies include wine, nachos and the occasional hibachi dinner.