Dirty sponges spread bacteria and germs to your counters and cooktops. A clean sponge can keep your kitchen safe and healthy for everyone who eats (or cooks) there.

By Maryn Liles
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Your kitchen sponge is one of the dirtiest parts of your home — just as dirty as your toilet, says a German study in Scientific Reports — which is especially horrifying when you think about how you use it to wash your dishes.

In fact, a report from the National Sanitation Foundation (NSF) International found that over 75 percent of all kitchen sponges had traces of coliform bacteria, a family of bacteria that includes Salmonella and E. coli, on them. That's why, in order to keep your trusty kitchen sponge germ-free, learning some sponge cleaning 101 can help.

From how often you should replace your sponge to the best types of sponges to use, this guide will help you learn how to clean your kitchen sponge effectively so you won't just be spreading germs around every time you do the dishes.

How often should you clean your sponge?

You should clean your sponge daily, according to the Academy of Nutrition and Dietetics. This will prevent germs and bacteria from growing.

Even if you're good about cleaning your sponge, be careful of cross-contamination. You should never use your dish sponge for any purpose beyond the dishes, like cleaning your countertops or to wipe down your cutting board, which could spread germs. And never use your sponge to clean up eggs or raw meat, either; disposable paper towels are the best choice.

How often should you replace your sponge?

You should replace your sponge every week, according the team of German researchers who studied the microbiology of dirty sponges at length. And if your sponge starts smelling before that, toss it. That's a sign something might be growing!

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How to Clean a Kitchen Sponge

The 2 best methods for how to clean a kitchen sponge are in the microwave or dishwasher, says the U.S. Department of Agriculture (USDA), since they kill over 99 percent of all harmful bacteria.

1. In the microwave

According to the USDA, zapping your damp kitchen sponge in the microwave for a minute at full power kills 99.9999 percent of all harmful bacteria, including E. coli. However, other studies say two full minutes is better. Place your sponge in a microwave safe-dish and, once it's done, allow it to cool completely before squeezing out the excess water.

2. In the dishwasher

Running your sponge through a wash and dry cycle in your dishwasher is also incredibly effective, according to the USDA, since this method kills 99.9998 percent of all bacteria. Just make sure your dishwasher is set to the "heat dry" setting to get all the microbe-killing effects.

What types of sponges are the cleanest?

Some types of sponges are naturally cleaner than others. The most common type of sponge is cellulose, which is made from wood pulp. Cellulose sponges can come with an abrasive scouring material attached to one side or not.

They're great because they're cheap and effective, but on the downside, they're quite porous so they tend to trap food particles. Plus, they're ultra absorbent and tend to hold water, which means they're quick to become a breeding ground for bacteria.

A smarter choice would be a sponge made of a synthetic material, like a silicone scrub pad or a sponge made of polymer foam, like Scrub Daddy, since they're made of nonporous materials.

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