There's really only one way to ensure it's good to go.
Many people think microwaving kitchen sponges or throwing them in the dishwasher are the best 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% of bacteria. In fact, sponges that were cleaned in the microwave or dishwasher actually contained higheramounts of bacteria, according to their research.
The experts actually tested the best ways to sanitize kitchen sponges and found that mixing 3/4 cup of bleach in one gallon of water and soaking the sponge for five minutes was most effective.
They also found that microwaving and the dishwashing could be effective, zapping 99.9% of germs from the home-used sponges and from the lab-treated scrub sponges. However, on the lab-treated cellulose sponges, microwaving just missed the mark for E. coli (99.83% reduced), and the dishwasher didn't quite get all the salmonella or E. coli (99.88 and 99.86% reduced, respectively).
No matter how diligent you are about cleaning, your kitchen sponges won't last forever. Clean sponges weekly and toss shabby ones (about every two to three weeks, depending on use).