When to Replace a Kitchen Sponge, According to a Germ Expert

Take a moment and survey your kitchen sink. Dish soap, perhaps gloves, a scrub brush—and that sponge. How long has it been there? Can you recall? Does it matter? If you’re wondering when you should throw out your sponge, the answer is obvious, and not as literal as you may think. 

For those of you going on week ??? with the same kitchen sponge, you’re not alone. It can be difficult (read: inconvenient) to part with a household item that gets the job done, and we’re huge advocates of making the most of what you have on hand. Plus, you’re using the sponge to clean, which implies that it’s clean too. Right?

Very, very wrong. 

Studies have shown that after a certain amount of time, your sponge (and the bacteria that it's housing) may actually do more harm than good. Read on to find out how often you need to ditch your kitchen sponge—and why.

The Bacterial Grossness of Kitchen Sponges

Your favorite cleaning tool is a hotbed for bacterial growth. Sponges have been shown to carry over 45 billion different kinds of bacteria per square centimeter. Fun fact: That’s more bacteria than in your toilet. 

According to author and microbiologist Jason Tetro, sponges can be one of the germiest items in your home. He emphasizes that thankfully, the majority of these bacteria are harmless to humans. But on rare occasions, harmful pathogens like Salmonella, E-coli, and Staph have been observed growing on damp sponges. 

How to Disinfect a Kitchen Sponge

Before you run to the kitchen and toss your sponge, know that it can be sterilized—to an extent. Tetro says that a temperature of more than 160 degrees should do the trick.

Place a damp sponge in the microwave on high for two minutes to clear most of the bacterial load. Putting your sponge in the dishwasher or boiling it in water are two effective alternatives. Rinsing and wringing out your sponge after each use can also increase longevity.

Although proper care and sterilization do work to extend its lifespan, it won’t make your sponge last forever. It will eventually need to be discarded.  

When Should You Throw Out Your Sponge?

Some recommend throwing sponges away after two weeks of use; others say it can last a month, but no longer. A good rule of thumb is to toss your sponge when it starts to tear or develops a strong odor. 

Per Tetro, microbial numbers won’t drastically change between uses, so exact timing is hard to pinpoint; he recommends throwing out your sponge when it starts to look worn or is no longer functioning well.

Many traditional kitchen sponges contain polyester or nylon, which—because they're forms of plastic—won't break down in landfills. So when the time does come to buy something new—or if that time is now—consider a more sustainable cleaning tool to replace it.

Eco-Friendly Kitchen Sponge Alternatives

1. Sqwishful Kitchen Essentials Set, $30

These all-natural brushes are made from plant-based materials such as hemp and bamboo. Although this set does include a sponge or two, proper sanitization will help keep bacteria at bay. 

2. Dropps Kitchen Brushes, $24

These plant-based bamboo brushes from Dropps are your ticket to a deep clean. The soft bristles are crafted of coconut fiber, making them gentle and sustainable.

3. Grove Co. Bubble Up Dish Soap Dispenser and Brush, $16

This tiny brush is built to fit right in the palm of your hand, making cleaning easier and more comfortable than ever. Plus, it’s crafted from sustainable materials like bamboo and recycled plastic. Just push down on the recycled spring and let the dish soap dispense.