Does Boiling a Sponge Kill the Germs That Are Living Inside It?

As kitchen sponges get wet and saturated with food residue, they become a hotbed for bacteria. The bacteria build up and create those musty odors, which aren’t just unpleasant but can be hazardous to your health. That’s why it’s so important to clean and sanitize your sponges often, especially after every use or when you notice foul smells. You can do so by soaking them in boiling water or by microwaving them. But does boiling a sponge actually kill the germs that are living inside it?

A 2017 study found that fecal coliform bacteria—the same type of E. coli that causes diarrheal illnesses—lived in more than 44 percent of household sponges. Other types of bacteria, such as Enterobacter cloacae, which can cause skin and abdominal infections, and Klebsiella oxytoca, which can lead to a UTI (urinary tract infection), were also found in sponges.

That’s why it’s so important that you clean and sanitize your sponges regularly, ideally every day or after each use. You can do so by soaking them for a minute in a bleach concoction or by microwaving them. Both of these methods are more effective than just rinsing your sponge with soapy water or placing it in the dishwasher, according to the Healthy Home and Garden website.

If your sponges are super soiled, it may be best to just toss them out and invest in some new ones. However, if they’re a bit more ragged but still in good condition, you can sterilize them and keep using them. Just make sure you’re cleaning them regularly and not letting them touch raw meats or fish or anything else that could introduce more bacteria into your kitchen.

Alternatively, you can try soaking them in a solution of one quart water and three tablespoons of bleach, which is recommended by the Better Homes and Gardens website. This method takes just a few minutes and can kill a variety of bacteria, viruses, mold, and mildew. You can also put the sponge in a damp microwave for two minutes to sterilize it, but this method won’t remove food particles and only works if the sponge isn’t too wet. Just be careful, since a dry sponge in the microwave can start a fire!