'Soap doesn't kill anything': How to hand wash your dishes and spread fewer germs

A woman washes dishes using soapy water. (iStock/Gilaxia)

When you think about the dirtiest surface in your home, you likely think of a deep, round, lipped basin that water flushes through.

No, it’s not your toilet. It’s your kitchen sink.

Despite the stomach-churning effect questionable bathroom cleanliness may elicit, several studies have concluded that the kitchen is actually the most germ-infested room in the home.

Potentially dangerous bacteria have been found to not only frequent the space where you prepare and eat food, but also the place where you wash your dishes.

“There is more fecal bacteria in the kitchen than there is in the bathroom,” Dr. Charles Gerba, renowned germ researcher and professor of microbiology at the University of Arizona, told CTVNews.ca.

Widely-cited research by Gerba, published in 1998, found that kitchens were more heavily contaminated with bacteria—including fecal bacteria—than bathrooms, with the toilet seat being the least contaminated site. The study found that the most contaminated surfaces included the kitchen sponge, the dishcloth, and the sink drain area.

With that in mind, CTVNews.ca asked Gerba and two food safety experts to weigh in on the most hygienic way to hand-wash dishes.

We asked whether you should soak your dishes in hot water; if the splatter from dirty dishwater can spread germs; and if we should do away with sponges once and for all. Here are some of the most important takeaways.

‘Soap doesn’t kill anything’

Don’t be fooled by soaps labelled antibacterial. According to experts, one of the most common misconceptions about dishwashing can be summed up in one quote: “Soap doesn’t kill anything.”

“Soap is not a sanitizer. It’s not intended to kill microorganisms,” Claudia Narvaez, food safety specialist and professor at the University of Manitoba, explained to CTVNews.ca.

“It will kill some bacteria, but not the ones that are more resistant to environmental conditions, like salmonella or E. coli.”

But that’s not to say that you should forgo the suds the next time you fill up the sink. Dish soap acts as a degreaser, allowing food particles and fat to be removed from your dishes and cooking utensils.

Without soap, you may leave behind traces of organic matter—the perfect breeding ground for bacteria, according to both Narvaez and Gerba.

“I’d wash your dishes within half an hour, otherwise bacteria will start to grow,” Gerba said.

Use bleach or hot water for true sanitization

Both food safety experts we spoke with agreed that the only way to truly sanitize your dishes when hand washing is to soak them in hot water, or a diluted bleach solution—especially when working with raw meat.

“When you’re working with chicken you’re right to soak it—but don’t soak it in soap because it won’t do anything,” explained Keith Warriner, professor of food safety at the University of Guelph.

“Plus, if you just soak it in soapy water and it splashes, you now have salmonella everywhere.”

After washing your dishes with soap and water to remove any left-over gunk, Warriner and Narvaez both suggest soaking them in warm water and one teaspoon of bleach to sanitize. If you’re wary about using bleach, soak dishes in hot water (at least 77 degrees Celsius) for two minutes to kill any remaining bacteria.

But does the average person really need to sanitize their dishes? Not all experts agree.

“Unless you are immunocompromised, or have small children, I don’t think you need to do that,” Gerba said.

“I would do it if I had elderly people in the home, or children under 5 years old, because you want to reduce any errors that occur.”

However, all three experts agree that it’s important to disinfect your kitchen sink and surrounding countertops at least once a week to kill off any harmful bacteria.

Ditch the sponge

Despite Gerba being more laid back when it comes to dishwashing, his research does give germaphobes a little retribution.

“In terms of fecal bacteria in the kitchen, the sponge is number one and the sink is number two,” he said, noting that in previous studies he found traces of salmonella in 15 per cent of household kitchen sponges.

If you choose to use a sponge, experts suggest changing your sponge every week, or opt for a plastic brush instead. The plastic bristles dry quicker, allowing less chance for bacteria growth.

Whatever you do, make sure your dishes dry properly

When it comes to hand washing, the most important factor in killing germs is a good air dry.

All three experts agree that using a drying rack yields the best, germ-free results.

But, whatever you do, don’t pick up the tea towel to get the job done quicker. According to both Narvaez and Warriner, if you use a towel to dry the dishes, you are essentially undoing any of the work you’ve done.

“That tea towel is used for everything and no one can remember when it was last washed,” said Warriner.