For years we all thought microwaving our kitchen sponges or throwing them in the dishwasher were effective ways to kill bacteria, make 'em smell better, and help them last just a bit longer, but it turns out, not so much.

Sponges that were "sanitized" in the microwave or dishwasher were just as bacteria-loaded as sponges that were never cleaned at all, according to a new study conducted by German researchers from the Faculty of Medical and Life Sciences and Furtwangen University. And if that doesn't make you cringe, this will: The sponges they examined were dirtier than a toilet.

"Despite common misconception, it was demonstrated that kitchen environments host more microbes than toilets. This was mainly due to the contribution of kitchen sponges, which were proven to represent the biggest reservoirs of active bacteria in the whole house," the researchers wrote in the report.

The researchers found that microwaving the cleaning tool only killed around 60 percent of bacteria. In fact, sponges that were cleaned in the microwave or dishwasher actually contained higher amounts of bacteria, according to their reseach. The experts found that several germs survived microwaving and even boiling, and then grew and spread quickly on the sponge.

Sponges are a hot spot for bacteria like salmonella, E. coli, staphylococcus, and much more. There's been evidence that using a bleach solution is the best way to clean a sponge, but truly, the only way to ensure you're working with a clean sponge is to replace it once a week. "From a long term perspective, [these] sponge sanitation methods appear not sufficient to effectively reduce the bacterial load in kitchen sponges and might even increase the shares of [disease]-related bacteria," the scientists wrote in their report. "We therefore rather suggest a regular (and easily affordable) replacement of kitchen sponges, for example, on a weekly basis."

So, if you want to avoid spreading disease-causing bacteria, it's best to throw your sponges out after a week of use (two, if you're pushing it). But for less than $1 apiece on Amazon.com, at least you can save while you stock up.

BUY NOW: $15, 20-pack of scrub sponges, amazon.com

(h/t New York Magazine)

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Jessica Leigh Mattern
Web Editor
Jessica Leigh Mattern is a web editor and writer who covers home, holiday, DIY, crafts, travel, and more lifestyle topics. Prior to working for Country Living, she wrote for several lifestyle and women’s magazines including Woman’s Day, Cosmopolitan, and Redbook