“Sponges are the perfect incubators for germs and mildew. Never wipe your counters with a sponge–you’re smearing germs everywhere.”
I’ve always known that wet sponges were big germ factories! Pick up a sponge that has been left wet in the sink and smell it—Phew!
So periodically, I threw my sponges in the laundry and washed them with my clothes. Bad idea, adding more germs to my dirty laundry. The washing machine doesn’t always get those germs out. And if I leave the clothes in the washing mashing machine before drying, incubating germs in my laundry.
(If you put enough bleach in your laundry, you’ll kill the germs.)
So, I started reading. We should consider sponges as consumables. Throw them away as soon as they start to smell; keep them no longer than a couple weeks, and sanitize them often.
You can sanitize a wet sponge in the microwave—but then you’ve got to remember to put them in the microwave and take them out without burning yourself. And never microwave a dry sponge—it may catch fire.
To me a much more realistic approach is to put them in the dishwasher on the top rack with your dishes. Then it’s just part of doing the dishes. The wash cycle should remove most of the food particles and a hot drying cycle will kill any remaining bacteria.
And put sponges on your shopping list. Buy inexpensive ones in bulk so you won’t flinch when it’s time to throw them away.
There, now you can keep your germ factory under control.
Sanitizing Kitchen Sponges, Michigan State Extension Service