From everything in your house, kitchen sponges have probably never been near the top of your list of being a dirty health hazard.
A 2017 study published in the Scientific Reports shows kitchen sponges should ideally be replaced weekly. Many people think throwing it in the washing machine or dishwasher will revive them. Sadly, the German scientists report proves otherwise. During their research they found 46 billion bacteria per square centimetre, spanning 362 different species.
A previous report has shown that kitchen sponges contain more active bacteria than anywhere else in the house - including the toilet. Sadly, they also harbour pathogenic bacteria like E.Coli and Salmonella. Sponges are “the biggest reservoirs of active bacteria in the whole house,” the authors write.
The 2017 study suggests using a new sponge every week. Unfortunately most kitchen sponges are made from plastic which will end up in landfill. 52 sponges a year per household. That's a lot of plastic ending up in landfill.
When looking for kitchen sponges it's worth looking for 100% plastic-free, compostable and biodegradable alternatives. That way there is no guilt in replacing them weekly. You can throw them in your compost heap or put it in your council compost / food-waste collection.
But most of all - toss out that kitchen sponge!