How to Deep Clean a Stinky Kitchen Sponge

Gerba has discovered that usually there are about 200 times more fecal bacteria on the average kitchen cutting board than on a toilet seat. DG FotoStock/Shutterstock

When asked, “What is the dirtiest spot in the typical household?” most people say the toilet seat. For sure, that would have been my response, until I discovered studies on bacteria and household diseases by Dr. Chuck Gerba, professor of microbiology at the University of Arizona. According to him, the filthiest place in our homes is the kitchen sponge or cloth.

Gerba’s studies have found that on the average toilet seat, there are 50 bacteria per square inch. But the typical kitchen sponge has around 10 million bacteria per square inch. That’s no typo! And it gets worse, so brace for what I am about to tell you.

Gerba has discovered that usually there are about 200 times more fecal bacteria on the average kitchen cutting board than on a toilet seat. He says that in the kitchen, it doesn’t necessarily get there through actual contact with feces, but arrives via raw meat products or the organs from inside of the animal, where a lot of the fecal bacteria originate.

Think about this scenario: You open a package of ground beef on the cutting board, form patties for tonight’s meal, wipe down the cutting board with your handy kitchen sponge and move on to chopping vegetables. Dr. Gerba says, given what he has discovered on the typical kitchen cutting board, the home’s toilet seat would be a safer place to cut vegetables.

Microwave

With all those gazillions of bacteria on kitchen sponges, you may assume the best way to clean our kitchen sponges is by a minute or two in a microwave oven set on High. Seems reasonable, right? Well, it’s not!

The amount of time needed in a microwave to reach the desired temperature to kill the bacteria and mildew harbored in the center of a sponge will result in a flaming, incinerated sponge. As reported in a study reported in The New York Times, nuked kitchen sponges still harbor about 40 percent of their bacteria, some of which can be life-threatening.

Dishwasher

Putting that kitchen sponge through a complete cycle with detergent daily, or as often as you run a load of dishes, is a much better solution. The heat plus detergent are sufficient to kill bacteria and mildew.

I’m going to assume that you use one kitchen sponge at a time, and that may be the problem. Let me suggest you have at least two sponges going. This way, one will always be available to wipe the counter and so forth, while the other is getting sanitized in the dishwasher. Just get into the habit of adding one kitchen sponge to every dishwasher load. Do this without fail for a couple of weeks, and soon it'll become a habit.

Antibacterial Solution

Another option, especially if you don’t have a dishwasher, is to soak that daily sponge in a good antibacterial sanitizer for at least 10 minutes up to overnight. But don’t spend $8 for a 16-ounce bottle from the store. Make it yourself for pennies!

According to the Food and Drug Administration1, 1 teaspoon of liquid chlorine bleach per 1 quart of clean water can be used to sanitize all kitchen surfaces such as cutting boards, countertops, refrigerator shelves—and sponges!

All that being said, another option is to replace sponges with cotton or microfiber cloths that get tossed into the laundry after every use.

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