Your dish sponge is definitely as dirty as your toilet: here’s how you should clean it

It’s funny, but when you do the dishes, do you really clean it or do you make it even dirtier? Depends. Enough to? From the state of the sponge we are using for the task. Yes, because depending on its wear and the way in which it is maintained, it could go from shiny plates to real pots.

Am I exaggerating? Not so much if we stick to what studies indicate, such as the one published in the journal Scientific reports , where a team of German microbiologists performed DNA analysis on sponges from different homes. They detected 362 different types of bacteria there, more than those usually harbored in toilets. This could mean two things: either the Germans are dirtier than you think, which is unlikely, or your dishwashing sponges may be dirtier than your toilets.

Although most of these bacteria do not represent a higher risk, others with pathogenic potential have been detected, including staphylococci, salmonella and E. coli, which could cause problems in the body of varying severity, such as as diarrhea, urinary tract infections, respiratory diseases and blood infections.

“Despite common misconceptions, kitchen environments have been shown to harbor more microbes than toilets. This was primarily due to the intake of sponges, which represent the largest reservoirs of active bacteria throughout the home,” says the German study.

What is all this? According to another investigation, this time from the Department of Biological Chemical Sciences at the University of Sonora, Mexico, the porous material with which dishwashing sponges are made and the humidity housed therein function as an incubator for the microorganisms. The problem is that when you use it again, you run the risk of spreading them on different surfaces.

“Humidity is what microorganisms love the most,” says the chef and science communicator heinz with . “But sponges also accumulate organic food remains, which are food for microbes.” In short, a perfect breeding ground.

The washing up sponge isn’t the only item that acts as a double agent in the kitchen. Absorbent terry cloths, used to clean surfaces, also work as an incubator for bacteria. “The biggest risk is biological cross-contamination. Often, by using the cloth, more is contaminated than what is cleaned,” says Wuth.

We know it: doing the dishes can be a tedious task. This means that many times dirty dishes remain piled up in the dishwasher until the next day. If the sponge is in the middle of all that buildup of moisture and organic remains, we’re playing with fireblight.

“The main cause of poisoning in homes is poor handling and poor hygiene,” adds Wuth. “It goes beyond how we prepare food: it has to do with how we clean surfaces and utensils,” says Heinz Wuth.

For example, says the cook, “if I have a very dirty sponge and I clean a glass with it, even if I rinse it well, there is a small chance that the bacteria will remain there. And surfaces are more likely to suffer from cross-contamination if a dirty cloth is used to clean them.

According to the study published in the Scientific reports, cross-contamination could not only occur on surfaces where contaminated utensils pass, but also in the hands of those who use them and in the food prepared there. This “is considered to be one of the leading causes of foodborne disease outbreaks”.

It is therefore a mistake to leave the sponge and the absorbent cloth in the same dishwasher, a fortiori in dirty water. In addition, the useful life of these products is shortened and they begin to generate aromas — a great sign of the proliferation of microorganisms — which are then transferred to the objects that one tries to clean. “And nobody likes to drink water from a glass that smells like rotten sponge,” Wuth says.

It will seem like a truism, but given the scientific background exposed, it is best to go back to the first units of our cleaning manual and double-check the practices.

First, the sponge, also known as the scouring pad – some may feel represented here – which is generally used to clean dishes, cutlery and other tools such as pots, pans and the dishes. For this, it is necessary to apply detergent or dish soap and water (hot if possible). They are found in various materials: there are natural fibers (such as loofah), or artificial fibers such as polyester or polyamide, the latter being the most common in homes and on the market.

“Sponges, in general, have a soft part and an abrasive part. The first is for general washing and the second is for when there is very stuck-on dirt. And for it to work, it must be accompanied by a good dishwashing detergent. Ideal for using hot water, as it removes dirt and grease more easily. Although this can also be done with cold water, this is no problem,” says Heinz Wuth.

Absorbent cloths, on the other hand, are generally made of natural cellulose fibers, and are used for cleaning surfaces. They’re not recommended for washing dishes, although, says Wuth, some people use them for that purpose. The important point is that this type of utensils should be used for exclusive tasks. Using the same cloth to clean the floor, which got wet while you were washing dishes, then drying the cabinet next to the dishwasher is like having a microorganism convention in your counter.

The same caveat goes for the kitchen sponge. If it is used for washing dishes, it remains only for this task.

It is normal to believe that the sponge, when used with detergent and water, cleans itself automatically. The reality can always be more complex than it seems, because the sponge, as well as the absorbent cloth, also need and must be washed and disinfected frequently.

There is a myth that the sponge can be cleaned by putting it in the microwave for a few minutes. Which is pretty true, according to Wuth. To do this, says the cook, you need to make sure there are no organic leftovers in sight. “There are three minutes at maximum power, then we let it rest for a minute,” he adds. This will allow you to keep it relatively clean for a few weeks.

If you use this method, make sure the sponge is dry. If it retains a lot of moisture, you could burn yourself removing it from the microwave.

In any case, you should know that this is not a 100% effective method. The German study specifies that the microwave does not eliminate all the bacteria and micro-organisms that live there. To be exact, it would only process about 60% of them, or more. The problem, more than the percentage, is that there is a possibility that the bacteria that survived this attack will become stronger and recolonize the sponge.

Considering the above, if the sponge you have in the kitchen stinks or emits aromas that are not typical of detergent, it means that it is infected and it is too late to put it in the micro- waves. Its only destination is the trash can.

More efficient than the microwave does a job of washing and disinfecting. Understand that to wash, as Wuth teaches, is to remove the remains visible to the eye and to disinfect by doing the same with those which are invisible to the eye.

First of all, the specialist recommends washing the sponge well, with the same detergent or soap as that used to clean the dishes. “And once it’s rinsed relatively well, you can add 70% (minimum) alcohol to sanitize it.”

Some do this by dipping the sponge in a solution of water and alcohol. But it is better, according to Wuth, to do it with a spray or an atomizer. This way, he says, less alcohol is wasted without losing efficiency in the task of disinfecting the sponge.

In the case of the absorbent cloth, after the respective washing with the detergent, it is also a good alternative to apply alcohol on both sides. And once the two utensils have been washed, they must be dried by pressing them to get rid of the water and letting them “dry” in the open air to eliminate any moisture.

Another method is that suggested by the University of Sonora : consists of immersing the sponge for at least 30 seconds in a solution of water and chlorine (in a ratio of 9 to 1), then letting it dry.

Washing and sanitizing methods give these utensils a useful life of a few weeks. However, it would be a mistake to claim that they can be made eternal in this way. Experts estimate that you should change them every 15 or 30 days, although this depends, according to Wuth, on the use, the intensity and the quantity of dishes washed daily, among other factors.

Microorganisms begin to appear from the first use, so it is important to constantly assess the condition of these products, checking that there are no red flags. For example, if the abrasive fiber begins to separate from the rest of the sponge, or if fiber balls or knots begin to form; if it begins to lose its original color, has a bad odor, is sticky to the touch or if black or white spots are observed on its fiber. All of these signs show that the sponge has already given all it had to give, and no matter how much love you have for it, it’s better to take it out.

As these utensils are disposable —even if it is expensive, you have to know how to say goodbye—, it is advisable to choose those which are biodegradable. Wuth, for example, recommends compostable cloths made of absorbent cotton and natural fibers, which can be disposed of in organic trash cans.

Sponges made with copper nanoparticles, on the other hand, have a higher antibacterial power than other materials, which gives them a longer lifespan and prevents the appearance of bad odors.

You can also opt for brushes. “I highly recommend them, especially for people who don’t like to touch food with their hands while washing dishes. The good thing is that they do not retain water and do not damage delicate surfaces, such as Teflon. In addition, they have a long shelf life. I’ve had one for five years, because I disinfect it every six months,” concludes Wuth.

*Prices for products in this item are updated as of May 19, 2023. Values ​​and availability may change.