Microwave sponges: two minutes on full

Health concerns aside, you can save money on sponges ...

Microwaves turn kitchen cloths into germ killers | the Daily Mail

...Two minutes of microwaving on full power mode killed or inactivated more than 99 per cent of all the living pathogens in the sponges and pads.

The Bacillus cereus spores required four minutes for total inactivation.

Professor Bitton said the heat, rather than the microwave radiation, was the most likely cause of death for the pathogens. As the microwave works by exciting water molecules, it is better to put wet rather than dry sponges or scrub pads into the oven.

... Cooks should microwave their sponges every other day, he suggested.

The warm, damp environment of kitchen cloths is the ideal breeding ground for microbes.

In the right conditions one bacterium can multiply to more than four million in just eight hours. This can make them up to 200 times more infested than a lavatory seat.