your kitchen sponge is responsible for more bacteria than your toilet

no matter how much you boil it, or even microwave it, that little square of foam is a giant receptacle for dangerous bacteria.

by nick beare

published mar 18, 2022

2 minute read

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2 minute read

join the conversation

your kitchen sponge is responsible for more bacteria than your toilet

'kitchens and bathrooms have a high potential to function as ‘microbial incubators,' experts say. getty

i like to do dishes. my kitchen has featured all kinds of tools and scrubbers to get my dishes squeaky clean: brushes with thick, tough bristles, scouring pads, steel wool and, of course, the classic sponge. i like the sponge. i have one attached to a handle filled with dish soap so it auto-lathers — sounds like it should be squeaky clean, doesn’t it? but it turns out that kitchen sponge is full of harmful bacteria, the kind that takes a whole lot more than soap to get rid of.

one 2017 study out of germany found that kitchen sponges were responsible for housing the most active bacteria in the whole house.

“kitchens and bathrooms have a high potential to function as ‘microbial incubators’, due to the continuous inoculation of new microbial cells,” the researchers wrote, “despite common misconception, it was demonstrated that kitchen environments host more microbes than toilets … this was mainly due to the contribution of kitchen sponges.”

don’t boil your kitchen sponge

so how do we disinfect sponges so that we aren’t smearing potentially harmful bacteria all over our dishes or kitchen surfaces?

you may have heard that boiling or microwaving your sponge for a minute or so can burn off the bacteria. however, the german study showed that not only does microwaving sponges not kill 100 per cent of the germs, but two types of bacteria were more prominent on the microwaved sponges than on unwashed ones.

“sanitation by boiling or microwave treatment has been shown to significantly reduce the bacterial load of kitchen sponges,” the researchers wrote, “however, our data showed that regularly sanitized sponges … did not contain less bacteria than uncleaned ones. moreover, ‘special cleaning’ even increased the relative abundance of both the moraxella– and chryseobacterium–affiliated otus.” (otu stands for operational taxonomic unit, a measurement used to classify types of bacteria)

the study concluded that no disinfecting method seemed to be able to reduce bacteria by more than about 60 per cent.

new sponges are better than old

so what’s the best way to keep your sponges clean? buy new ones.

it may seem like a defeatist attitude, but no used sponge is ever going to be 100 per cent sanitary so we should be diligent about replacing it more often. we should also be in the habit of wringing them out and letting them dry between uses. a wet, warm sponge is the perfect breeding ground for bacteria.

lastly, avoid contaminating your sponges. using one sponge for surfaces and another for dishes to cut down on the potential spread of bacteria between the two. and consider using a plastic or silicone brush to do the dishes instead of a sponge as the brushes generally stay drier, don’t have as many deep pockets as sponges and aren’t made of as porous a material.