Dirtier than water: how to clean and how often to change your sponge to do the dishes

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 it is maintained, we could go from shiny dishes to real little pots.

am I exaggerating? Perhaps, if we let ourselves be carried away by what happens on a daily basis in a good part of homes. Not so much if we stick to what studies like the one published in the journal Scientific reports , where a team of German microbiologists performed DNA analysis on sponges from different households. They detected 362 different types of bacteria there, more than those usually harbored in toilets. This can mean two things: either the Germans are dirtier than we think – which is unlikely – or the dish sponges can be dirtier than your toilet.

Although most of these bacteria do not represent a higher risk, other potentially pathogenic ones have been detected, including staphylococci, salmonella and E. coli, which could cause problems in the body of varying severity, such as diarrhea, urinary tract infections, respiratory and blood diseases. 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 Chemical Biological Sciences at the University of Sonora, Mexico, the porous material with which dishwashing sponges are made and the moisture lodged there function as an incubator for microorganisms. The problem is that when you use it again, you run the risk of spreading them all over different surfaces.

“Humidity is what microorganisms love the most,” says cook and science communicator Heinz Wuth . “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. Many times, by occupying the fabric, more is contaminated than what is cleaned,” Wuth explains.

We know it: doing the dishes can be a tedious task. This means that many times the dirty dishes stay piled up in the dishwasher until the next day. If the sponge sits in the middle of all that buildup of moisture and organic debris, 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 become contaminated if a dirty cloth is used to clean them.

According to the study published in Scientific Reports, cross-contamination could not only occur on surfaces where contaminated utensils have passed, but also on 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 objects that attempt to be cleaned. “And nobody likes to drink water from a glass that smells like rotten sponge,” Wuth says.

It may sound like a truism, but given the scientific background on display, it’s best to go back to the first few units of our cleaning manual and double-check the practices.

First, the sponge, also known as the scouring pad – some of you may feel represented here – which is generally used to clean dishes, cutlery and other tools such as pots, pans and pans. 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. It is ideal to use hot water, as it removes dirt and grease more easily. Although it can also be used with cold water, this is no problem,” says Heinz Wuth.

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

The same warning 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 somewhat true, according to Wuth. To do this, explains the cook, you must ensure that there are no visible organic remains. “It takes 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 support about 60% of them. 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.

Given the above, if the sponge you have in the kitchen smells bad or is expelling aromas that aren’t typical of detergent, that means it’s infected and it’s too late to put it on the mic. -waves. Its only destination is the trash can.

More efficient than the microwave is to do washing and disinfection work. Understand that washing, as Wuth teaches, consists in removing the remains visible to the eye, and to sanitize 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 that is used to clean the dishes. “And once it’s rinsed relatively well, you can add 70% (minimum) alcohol to get it disinfected.”

There are those who 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 squeezing them to release 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 thus be made eternal. 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 you see black or white spots 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 that are biodegradable. Wuth, for example, recommends compostable absorbent cloths made of 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 fairly long lifespan. I’ve had one for five years, because I disinfect it every six months,” concludes Wuth.

*Prices for products in this item are current as of September 7, 2022. Values ​​and availability may change.