Ask Zomet

Thank you for the question. Indeed I know of rabbis who permit washing both dairy and meat dishes in the same dishwasher, obviously after removing all vestiges of food whenever the dishwasher has been used. However, I would tend to forbid this, certainly as practical advice on an institutional level. My main reason is to avoid conflicts with the normal way that a kitchen is designed – in other words, this would be a policy decision. In our kitchens we keep separate dishes for everything, including pareve, and now, suddenly, how can we permit putting both dairy and meat dishes into equipment which might have food remaining between washing cycles, on the same day, and at a high temperature (halachically defined as so hot that a hand will be "scalded")?
 
From the halachic point of view, the main problem is food particles that tend to remain at the bottom of the dishwasher, sometimes even for days or weeks. This means that we are concerned not only about food traces absorbed in the walls but about actual pieces of food. In many homes which are not very particular, especially where young people live, dishes full of food are sometimes loaded into the dishwasher.
 
Those who would like to depend on various lenient opinions (based on the fact that any remaining food particles are spoiled by contact with detergent) should not be reprimanded as long as they make sure to remove any visible food that remains, and especially if they have separate trays for dairy and meat. As far as I am concerned, this is not a good policy, and I myself do not accept it (I have one large dishwasher outside the kitchen and another smaller one inside the kitchen, to provide easy access).