4 Easy Ways to Clean A Sponge

And how to know when your sponge is ready for retirement.

You guys, sponges are gross. Sorry to be the bearer of bad news but these little guys that we rely on to clean messes from our counters and scrub food from our dishes are actually total bacteria magnets. They harbor germs that can actually hurt us, causing E. coli and salmonella, among other various foodborne illnesses.

It’s not their fault, necessarily. Sponges mean well. They really do. But user errors tend to invite cross-contamination between counter messes and dish messes — and don’t get us started on how icky the kitchen sink can be.

NPR reported on a study published in Scientific Reports, that took a deep (like, really deep) dive into “how many critters are living in used kitchen sponges.” And the results were not pretty.

"We found 362 different species of bacteria, and locally, the density of bacteria reached up to 45 billion per square centimeter," says Markus Egert, a microbiologist at Furtwangen University in Germany, who led the study.

Our translation: If you scale that up, that's something like stuffing all the people who live in Manhattan into the Rockefeller ice rink.

Furthermore, the article quotes Egert, who adds, "That's a very huge number of bacteria, indeed. There's hardly any habitat on Earth where you'll find similar densities of bacteria, except for the human intestinal tract."

Wow, okay. So what to do with this information?

Why & How often to clean a sponge

This shouldn’t exactly be news to you, but sponges need to be cleaned, too. Sort of like how you’ve got to clean your dishwasher (and even the garbage disposal!) seasonally. Sponges should be deep cleaned weekly, if not every couple of days. And if sponges are stored appropriately and cleaned often, residing in a wire rack between uses (or anyplace where it’s able to dry thoroughly), your sponge may last you up to several months — but that doesn’t mean you should hang onto it for that long.

To be honest, we’d recommend getting a new sponge once a month, at the very least. It would not be unreasonable to replace your sponge as frequently as every 2-3 weeks. And prioritize having two sponges: one designated for the counter and one for dishes. Make them different colors to ensure no cross contamination occurs.

Before we get to the cleaning portion, a few quick sponge tips:

  • After each use, your sponge ought to be wrung out so that it’s merely left damp and able to air dry. Constant wetness (especially in warm environments) breeds germs and bacteria.
  • If you’ve got a window near your kitchen sink, we recommend leaving it cracked when the weather’s nice to assist in the air drying of your sponge.
  • We also suggest keeping your sponge away from any raw meat and its juices — use a paper towel when dealing with those types of messes.
  • If your sponge smells funky, toss it. Like, immediately.

How to clean a sponge

There are many ways to clean and (mostly) disinfect your sponge. Varying methods have varying degrees of effectiveness, which have been hotly debated by scientists and studies and occasionally blown out of proportion by misleading headlines, generating confusing conclusions. We’re here to assure you that each of these sponge cleaning methods have been proven to reduce the bacteria and germs on your sponge, at least to the point of making them safe for you and your family to use and not get sick.

1. How To Clean A Sponge In The Dishwasher

  • Rinse your sponge under the faucet to remove any loose debris.
  • Wring out the sponge and stick it on the top rack of your dishwasher.
  • Run the machine through on the hottest cycle available, using the heat dry cycle to finish.
  • Throw in an ActionPacs™ + Dishwasher Cleaner Action to clean the sponge along with your dishes while also working its magic to clean your dishwasher. It’s a two-fer!
  • Cleaning your sponge in the dishwasher will kill roughly 99.9% of germs.

2. How To Clean + Disinfect A Sponge Using Vinegar

  • Using full strength vinegar — which is more potent and acidic than white vinegar — soak your sponge for about five minutes.
  • Wring out the vinegar from the sponge thoroughly.
  • Rinse the sponge with warm water, squeezing it repeatedly to get rid of any vinegar residue.
  • Let sponge air dry.
  • Vinegar is both cheap and nontoxic, making it a perfect disinfecting agent.
  • Vinegar will kill 99.6% of bacteria in your sponge.

3. How to Clean + Disinfect a Sponge Using Bleach

  • Mix ¾ cup of bleach with 1 gallon of water.
    • *Note: Bleach is stinky and toxic, so do this in a well ventilated space.
  • Soak the sponge in the diluted bleach solution for about five minutes.
  • Wring out the bleach solution from the sponge thoroughly.
  • Rinse the sponge with warm water, squeezing it repeatedly to get rid of any bleach residue.
  • Let sponge air dry.
  • Bleach will kill 99.9% of bacteria on your sponge.

4. How To Clean A Sponge In Your Microwave

  • This is the method that has the most divisive responses. Some people want to argue that microwaving your sponge will actually make the germs and bacteria even worse, giving them a nice toasty incubator in which to thrive.
  • We assure you that microwaving your sponge will “knock down the bacteria living in it by about a million-fold,” according to scientists in the U.S. Department of Agriculture, as reported back in 2009. While the microwaving method “will leave many [bacteria] still alive… the heat will target the dangerous ones.”
  • Microwaving your sponge doesn’t sterilize it, but it will kill the bacteria that could make you sick.
  • Note: The sponge can and will burn if not microwaved correctly, especially if it’s dry.
  • Rinse the sponge under the faucet and wring it out so that it’s damp, but not sopping wet.
  • Put the sponge in a shallow microwave safe container.
  • Microwave the sponge for two minutes.
  • Note: Your sponge is going to be HOT.
  • Allow the sponge (and container) to cool for about ten minutes.
  • Once the sponge has cooled, wring out any excess water and let it air dry.

How Not To Clean A Sponge

We don’t recommend following the advice of anyone who tells you to clean your sponge by soaking it in lemon juice, essential oils or simply hot, soapy water. These methods have been proven to be ineffective and could result in actually causing your sponge to grow more bacteria, germs, molds and yeasts. No thanks.

When to throw a sponge away

  • Can’t remember when you last replaced your sponge? Time for a new one.
  • Do your hands smell weird and mildew-y after using your sponge? Yeah, bye.
  • Is your sponge visibly disgusting? Does it fall apart into pieces when you use it? Is it discolored? Trash it.
  • Can you smell your sponge from across the room? Nope. Garbage time.

Cleaning your sponge should become a basic part of your kitchen cleaning routine. Best to purchase sponges in bulk, so that way you’re not tempted to hold on to the same one for too long. Sponges have a short life span, and that’s okay. But you can certainly use these tactics to keep it clean before you cycle in a new one.

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