How often should you replace your kitchen sponge? - How To

Aug 13, 2026

Don’t sanitise it. Euthanise it.

There’s a sponge in the main office kitchen next to delicious. HQ. I call it the Sponge of Death. I don’t really know how long it’s been sitting there. Next to the sink. In the sink. Sometimes right in the plughole. I watch on in quiet horror as staffers from other departments blithely use it to wash their dishes, their mugs, their cutlery.

You would never catch me going near the Sponge of Death. Even if I were wearing surgical gloves and standing several feet away, poking at it with a very long stick. Because I know that kitchen sponges harbour a very dirty secret indeed.

How dirty are kitchen sponges?

Kitchen sponges can play host to hundreds of different species of bacteria – 362, according to a 2017 study published in Scientific Reports. Despite the fact that you regularly douse them in hot, soapy water, sponges provide the perfect environment for bacteria to grow and multiply – they’re damp, they’re porous and they contain tiny bits of food. Add the balmy room temperature of a kitchen, and you’ve got the ultimate microbe nursery school going on in there.

While most of the bacteria are harmless, some are not. Sponges can harbour pathogens like Campylobacter, Salmonella, Staphylococcus, E. coli and Listeria, which can increase the risk of making you, your family, or the entire Level 3 population of my office building very sick indeed. Except for me, of course. I will claim my rightful throne as Queen of Level 3, and trust me, the new administration has plans.

Doesn’t detergent keep a kitchen sponge clean?

Standard dishwashing detergents contain surfactants. Their job is to break down grease and lift food particles off surfaces so they can be washed away by water. They’re not designed to kill bacteria or act as disinfectants. Even antibacterial dishwashing detergent is rarely enough to kill all the bacteria hiding deep inside your sponge.

Detergents also help water penetrate more deeply, which means even more moisture going into – and staying inside – your sponge.

How often should I replace my kitchen sponge?

Experts recommend replacing your kitchen sponge every one to two weeks, depending on how often you use it. If your sponge sees action every day, weekly is your best bet. Always wring it out completely after using, and let it dry in a well-ventilated spot – never sitting in a puddle at the bottom of the sink.

If you notice your sponge developing a musty odour, this is caused by Moraxella osloensis, a bacteria that thrives in wet and porous environments. If your sponge smells, it’s already heavily colonised and needs to go.

How do I clean a kitchen sponge?

Some people suggest running your sponge through the dishwasher, popping it in the microwave or throwing it in the washing machine.

While these methods can kill off a significant portion of the bacteria your sponge contains, it rarely kills off 100 percent. What’s worse, studies have found that sanitising like this can sometimes only kill off the weaker types of bacteria, leaving the strongest ones behind. And with all the other competition gone, these super-strong strains then rapidly multiply and colonise your sponge.

Ultimately, kitchen sponges can be more trouble than they’re worth. You can invest in eco-friendly natural cellulose sponges to reduce the guilt of having to replace them so often, or simply switch to a dish brush, which dries much faster and harbours far fewer bacteria. Your immune system – and my future queendom – will thank you.