How come kitchen sponges are smelly?

I made a discovery about stinky sponges. I’ve always make a point of squeezing all the water out of a dish sponge so that it doesn’t sit and fester and smell. When I used to have a dishwasher, I would wash the sponge in it periodically to disinfect it with hot water. I have also sprayed the stinky sponge with bleach, which I don’t like to do because it gets a toxic chemical near our dishes.

For a few years now though the sponges in our house have not been stinky. I attributed this to vigilant sponge squeezing. We also have a little rack that hangs on the side of the sink to put the sponge in so it doesn’t sit stewing in water. The sponge used to really smell when I lived with my ex who would leave it in a puddle in the bottom of the sink. We’ve been apart for over five years now and the sponge hasn’t smelled since then. Keep it dry, keep it on the side of the sink. Problem solved, or so I thought.

Then I made an interesting discovery.

For the longest time, I purchased mainstream dish washing liquid  like Dawn™.  When I moved back home to Portland and was able to shop again at New Seasons, I started buying more environmentally friendly soaps that smelled really good like Mrs. Meyers Clean Day™. Oh, I love that soap. It’s not much more expensive than the mainstream stuff and it smells so delicious.

One day, we ran out of dish washing soap and I was at some store that isn’t New Seasons buying who knows what. The store didn’t have any options for dish washing soap other than mainstream brands. I bought a jug of Dawn™ and didn’t think much of it. It doesn’t smell pretty like Mrs. Meyers™, but we were out of soap and it was there so I bought it. I thought little of it beyond that.

Then a couple of weeks later, I realized that no matter how much I squeezed out our sponge, it smelled. Bad. I couldn’t figure why until I remembered the dish washing liquid change and wondered if this was what caused the smell to return so I decided to try an experiment.

I bought some more of the Mrs. Meyers™ environmentally friendly soap and started using it instead of the Dawn™. I did this for a week and the smelly sponge went away. I used the Dawn™ again for a week. The smelly sponge returned.

My conclusion?

Smelly sponges have nothing to do with how much water you squeegy out of them, they smell because of the detergent used to wash dishes. I have no doubt of this. I’ve tried a variety of different soaps including Trader Joe’s dish washing soap. No smell. Biocleen™. No smell. J.R. Watkins™. No smell. Seems to be the Dawn™ that makes the sponge smelly for whatever reason.

I still have the jug of Dawn™ under my sink way in the back. It’s there because I’m not sure how to dispose of it without putting it in a landfill and somehow that feels as bad as dumping chemicals in a landfill. I’m sticking with the good stuff. Dawn™ might “cut grease” but God only knows what else it’s doing that it allows bacteria to fester in the dish sponge and make it smell like old feet. Yuck. No, thank you.