A new study has found that kitchens host more bacteria than toilets, and it's mainly due to kitchen sponges which are "the biggest reservoirs of active bacteria in the whole house".
While it's common for people to boil or microwave their sponges to clean them, the study's authors, from three German universities, found it made little to difference to the amount of bacteria absorbed by a sponge.
They said not only do kitchen sponges hold bacteria, they also spread it across surfaces, which can lead to the cross-contamination of hands and food - a leading cause of food-borne disease outbreaks.
The authors concluded that cleaning sponges is not sufficient to significantly reduce the bacteria they contain.
"Our data showed that regularly sanitised sponges (as indicated by their users) did not contain less bacteria than uncleaned ones," the study said.
"From a long term perspective, 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."
They recommend replacing kitchen sponges on a weekly basis.
There are plenty biodegradable sponge options on the market, as well as non-porous sponges that don't harbour bacteria such as silicone sponges.
The study has been published in Scientific Reports journal.