BuzzFeed

Both the USDA and Good Housekeeping found this actually works; try to do it at least once a week, if not every three days or so. And if you heard that microwaving doesn't help, well — all those news reports were inaccurate.

(It's also essentially equally effective to run your sponge through the dishwasher, on the top rack, with the heat-dry setting, if you prefer to do that instead.)