Carbon filters generally need to be washed every three to four months—or more frequently if you cook often. Here you place it in a dishwasher and set the cycle to at least 70°C. You don’t have to use soap for this. Alternatively, you can rinse the filter under hot water without using a sponge. Place it in the oven after it’s been drained. Set it to 70°C and keep the filter in there for at least four hours. But once the filters stop absorbing the smell of food while you cook, it’s time to replace them.