The kitchen sponge you use to wash dishes or clean the counters should be replaced each week, according to a new study.



According to a newly published study from the online Journal of Scientific Reports , cleaning your kitchen sponge by microwaving or boiling it doesn’t significantly reduce bacteria and can even increase it, in certain cases. This is troubling, considering researchers also determined that these sponges are the “biggest reservoirs of active bacteria” in your household, making them even grosser than your toilet. 


One of the microbes, Moraxella osloensis, can cause infections in people with a weak immune system and is also known for making laundry stink, possibly explaining your sponge’s funky odor. Researchers made the discovery by sequencing the microbial DNA of 14 used kitchen sponges.

The researchers reveals that “Sanitation by boiling or microwave treatment has been shown to significantly reduce the bacterial load of kitchen sponges and can therefore be regarded as a reasonable hygiene measure. However, our data showed that regularly sanitized sponges did not contain less bacteria than uncleaned ones. 


Researchers also said that “special cleaning” of the sponges resulted in an increase in certain types of bacteria.


“Presumably, resistant bacteria survive the sanitation process and rapidly re–colonize the released niches until reaching a similar abundance as before the treatment,” the study said. “Although further analyses, including controlled sanitation experiments, are needed to substantiate these findings


“From a long-term perspective, sponge sanitation methods appear not sufficient to effectively reduce the bacterial load in kitchen sponges and might even increase the shares of RG2-related bacteria,” the study said, referring to Risk Group 2, the type of microorganisms that may be associated with human disease.

So instead of trying to save your sponge by cleaning it, researchers suggest you throw it away or a regular (and easily affordable) replacement of kitchen sponges, on a weekly basis.” 

If you’d rather not feel wasteful by throwing out a sponge every week, we suggest buying something non-porous, like silicone scrubber, to do your dishes.