Answer: Maran Ha’Shulchan Aruch (Yoreh De’ah Chapter 95) discusses the accepted form of dishwashing that was common in his days where soiled pots were placed into large vessels filled with boiling water and they were washed inside. Maran discusses washing dishes with meat grease stuck on them in a large dairy vessel with boiling water in it. He writes that this would certainly prohibit the large dairy vessel, for it will now absorb some of the meat grease which is in the boiling water within it and this constitutes absorption of meat and milk. However, Maran also discusses a situation where this will be permissible: “It seems to me that if one placed ashes in the hot water which is in the dairy vat before the meat dishes were placed in it to be washed, although meat grease may have been stuck to the dishes, this is permissible, for as a result of the ashes, this becomes a situation of absorbing a defective flavor.” This means that since ashes were placed in the water before the meat dishes were placed inside, the taste of the water has become quite putrid since the ashes spoil the water’s taste. Therefore, when the meat dishes with meat grease on them are placed in the water, the taste of the meat grease which is stuck to the dishes immediately becomes putrid as well and thus, the flavor that is being absorbed by the large dairy vat is a putrid flavor which cannot be considered a meat flavor. Thus, the large dairy vessel does not become prohibited at all.
We can infer from the words of Maran Ha’Shulchan Aruch regarding our case that since before the dishes are placed in the dishwasher the primary food particles are removed from them in order to prevent the machine from becoming clogged and only a small amount of residue remains, in addition to the fact that the water in the dishwasher is mixed with dishwashing detergent which certainly gives a putrid taste to the water and the dishes, it is permissible to wash meat and dairy dishes in the dishwasher even together, for Maran Ha’Shulchan Aruch has ruled that the giving off of a putrid taste is permissible. Many Acharonim rule likewise, including Hagaon Harav Yonah Navon in his Sefer Nechpa Ba’Kessef who writes that as long as the water was given a putrid taste, it is completely permissible to be lenient.
Although some Acharonim disagree with Maran, nevertheless, Maran Harav Ovadia Yosef Shlit”a writes lengthily to defend the words of Maran HaShulchan Aruch, whose rulings we have accepted upon ourselves. Thus, he concludes that according to the letter of the law, one may be lenient and wash meat and dairy dishes in a dishwasher even at the same time as long as the water in the dishwasher is mixed with dishwashing detergent. However, it is preferable to wash meat dishes and dairy dishes only one after another, for in this way, one avoids all concerns.
