Insights into Halacha

For the week ending 21 July 2012 / 1 Av 5772

The Dishwasher Debate - Part II

by Rabbi Yehuda Spitz
The Color of HeavenArtscroll

In part I we discussed the background and halachic rationales of why it might be possible according to certain opinions to wash milk and meat dishes together, including the essential laws of Nat Bar Nat. We also cited that the great Rav Moshe Feinstein zt”l, in numerous responsae,[1] ruled that one may actually use the same dishwasher for both milchig and fleishig dishes, provided that it is not used for both types of dishes at the same time and that it is cleaned out (along with an empty rinse cycle) in between uses. He also required one to maintain separate racks, one for exclusive use of the dairy dishes and one for the exclusive use of the meat dishes[2].

Still, many other contemporary authorities expressed reservations about Rav Moshe’s lenient ruling for various reasons[3]:

  1. Rav Moshe does not mention filters. Unless one constantly changes, or at least cleans out, the filters between loads, the dishwasher may be cooking that food residue into the next load of dishes, thereby creating a potential kashrus concern. (However, it must be noted that it is possible that when Rav Moshe wrote his teshuvos on this topic about forty-five years ago, filters were not standard on dishwasher models).
  2. There is always the possibility that actual food residue will remain on the dishes even after the wash cycle. This residue might have imparted a direct infusion of taste into either the walls of the dishwasher and/or into the next set of dishes placed inside when they will be washed, thus possibly causing the dishes to become forbidden.
  3. One of Rav Moshe’s provisos is that there must always be 60 times water present against the collected amount of food residue and particles on all the dishes[4]. However, this might not always prove true, especially with the smaller dishwasher models available these days. Additionally, even in larger models, some dishwashers slowly fill up and empty out with boiling hot water. The question of whether there is sixty times the amount of residue might actually depend on where the water level is at that time as it slowly fills up or empties out.
  4. Rav Moshe writes that concerning a dishwasher “even while in the boiling water, it is not considered actual cooking, for the water enters from another place”. This implies that he holds that the level of actual cooking of the water is only a kli sheini )a secondary vessel on which something hot was only placed, not actually cooked in),which, according to the basic halacha, is not considered genuine cooking.However, many current models first fill up with cold water and only afterwards heat up the water, making the dishwasher a kli rishon (the vessel in which something was actually cooked – similar to a pot on the fire), which is considered cooking according to all opinions, thus increasing manifold the likelihood of an impending kashrus risk.
  5. Many people do not understand the different nuances and fine distinctions in halacha and may very well come to being nichshal by using the same dishwasher for both sets of dishes.

As a result of the halachic issues raised, many contemporary authorities, including Rav Yosef Shalom Elyashiv shlit”a, Rav Shmuel HaLevi Wosner shlit”a, and the Ba’er Moshe, feel that a safeguard is necessary in order to lessen the probability of a potential kashrus pitfall. They therefore require one to purchase two separate dishwashers or dedicate the use of the dishwasher exclusively for either meat or dairy dishes, but not to use the same one for both sets of dishes, even consecutively[5].

Ashes Attack:

“Wait a minute”, one may ask. “What about the dishwashing detergent (or soap)? “Doesn’t that help out to make this whole issue less of a problem? In the very next paragraph after the discussion of washing dishes, the Shulchan Aruch[6] says that if ashes are added to the boiling water, then it prevents the transfer of taste – even by meat and dairy dishes at the same time! In other words – no harm no foul! Shouldn’t I be able to rely on this? Aren’t ashes equivalent to soap?”

Before we get to soap, the ashes issue is not so clear cut. For while the leniency of ashes is correct according to the Shulchan Aruch and other poskim who defend him[7], many authorities, most notably the Shach and Taz[8], maintain that there is no valid basis for such a ruling, and as such disagree with his hetter. Due to the staunch opposition to the Shulchan Aruch’s reasoning, some authorities endorse the hetter exclusively in extenuating and difficult circumstance or in case of great financial loss[9]. It would seem thatin accordance with this, one should not rely on this for a dishwasher l’chatchila.

Soapy Surprise:

Yet, the Yad Efraim, the Pri Megadim and other decisors qualify the issue. They maintain that this whole machlokes is only about mixing ashes into the boiling water. They explain that the dissenters are of the opinion that ashes do not do an adequate job of imparting repulsive and utterly inedible taste (rendering pagum). [If you think about it, it makes sense. We eat bread and eggs dipped into ashes on Erev Tisha B’Av without too many side effects.] On the other hand, since “our soap” does a much better job of it, as it most definitely is stronger and better at cleaning than ashes, everyone would agree that it has the ability to prevent the infusion of meat and milk taste to each other, thus averting any possible kashrus problem[10].

Rav Ovadia Yosef shlit”a cites this reasoning for his own ruling on dishwashers. He rules that although l’chatchila, if at all possible, one should be washing the meat and milk dishes separately, however, if one cannot, he may use the same dishwasher for both meat and milk dishes – even at the same time[11]! He maintains that dishwashing detergent most definitely is strong enough to be considered pagum according to all opinions, and he feels that the contemporary decisors who mandated separate dishwashers did not take the pagum factor into account.

Although other authorities, including his own son Rav Yitzchak Yosef shlit”a, employ similar logic and allow washing both types of dishes in the same dishwasher, they are of the opinion that one may utilize this leniency of dishwashing detergent exclusively for separate cycles[12]. Meaning, even though the detergent renders the water foul-tasting enough to prevent issur from happening, one is still required to wash the milk dishes and the meat dishes separately.

Nevertheless, other authorities are unconvinced by this reasoning and are reluctant to rely upon the hetter of detergent. They maintain that if there are large quantities of leftover food on the plates (more than a few crumbs or grease), then even after a full wash they remain intact and edible[13]. Additionally, even with smaller amounts of food residue, the plates do not always come out of the washer squeaky clean. This proves that the detergent does not always render the item pagum[14]. Others maintain that running both types of dirty dishes together and relying on the detergent to do its job by preventing the issur from occurring, falls under the category of “Ain Mevattelin Issur L’chatchila[15], and therefore it becomes prohibited to do so.

In the final analysis, although there undeniably is what to rely upon if stuck in a situation with one dishwasher, and especially b’dieved(and even if they were washed together, according to some poskim), all the same, most contemporary authorities advise that if at all possible, one should endeavor to procure two separate dishwashers, one for milk and one for meat, in order to prevent potential pitfalls in kashrus[16].If that’s not possible, there is always the good old fashioned do-it-yourself (or do-it-your-spouse) “elbow grease”in the kitchen sink. You never know, this might also be the reason that disposables were created.

Important Note: The halacha presented here is simplified to present the issues in a comprehensible manner, so that the reader may gain an appreciation for and understanding of the halachic process and is in no way meant to convey final psak halacha. Therefore, one must make sure to ask a competent halachic authority for guidance in each individual situation or in case of an actual sheilah.



1Shu”t Igros Moshe (O.C. vol. 1, 104 s.v. uvadavar; Y”D vol. 2, 28 & 29; Y”D vol. 3, 10, 2; ibid 11; ibid. 58 s.v. vchein).

[2]The need for a second set of racks according to Rav Moshe’s opinion is because since the dirty dishes sit directly on them, they will more readily absorb direct ta’am from the food residue. Therefore, if one would place dirty milchig and fleishig dishes on the same rack, (even in two separate cycles), this may result in the racks absorbing both meat and dairy taste. This then transmits together to the dishes in a subsequent load as ta’am basar b’chalav.

3 See Shu”t Ba’er Moshe (vol. 7, 60), Shu”t Beis Avi (vol. 2, 93), Shu”t Avnei Yashpei (vol. 3, 71), Yalkut Yosef (IV”H vol. 3 pg. 491, s.v. ulam), Badei Hashulchan (Y”D 95, 81; Biurim pg. 309, s.v. u’linyan), Pischei Halacha (English version ppg. 258 - 262), Kitzur Shulchan Aruch (Pfeiffer, on BB”C vol. 2, Kuntress HaBiurim 6), Kovetz M’Beis Levi (vol. 1, HaKashrus HaMitbach pg. 30, 7, footnote 6), HaKashrus (Ch. 1, pg. 75 -76), Kashrus V’Shabbos B’Mitbach HaModerni (pg. 114), Ohel Yaakov (on IV”H 1st edition pg. 296 - 297, 26, footnotes 52 & 53).

[4]This is the standard rule of nullification in halacha.If there is present 60 times the amount of non-kosher, then it is considered nullified. See Shulchan Aruch Yorah De’ah 98.

5See last footnote. Others include the Beis Avi, the Avnei Yashpei, and the Badei Hashulchan. The majority of poskim rule this way as well, that although one may rely on Rav Moshe’s ruling m’ikar hadin, nevertheless, if at all possible one should have separate dishwashers for meat and for dairy dishes.

[6]Y”D 95, 4.

7Including ad loc. - the Kreisi U’Pleisi (4, and in Matteh Yonason s.v. yireh), Chacham Tzvi (Shu”t 101), the Ya’avetz (s.v. yireh), Pri Toar (6), Knesses HaGedolah (Hag’ B”Y 46), Damesek Eliezer (cited by Knesses HaGedolah), Knesses Yechezkel (Shu”t 28), Tzemach Tzedek (Shu”t 91), Minchas Yaakov (55, 20), Imrei Baruch, Levushei Srad, Chida (Shiyurei Bracha 4), Beis David (Shu”t Y”D 41), Shaagas Ayreh (cited in M’dei Chodesh B’Chodsho vol. 2, Piskei Halachos 93), Erech Hashulchan (Y”D 107, 1), Shulchan Gvoah, Zivchei Tzedek (38), Eidus B’Yhoseif (42), Matteh Yehuda (452, 5) and Kaf Hachaim (56).

8Including the Shach (Y”D 95, 21), Taz (ad loc. 15), Rashal (Yam Shel Shlomo, Chullin Ch. 8, 94), Levush (Vol. 4, 135), Gr”a (24), and Mishmeres Shalom (Y”D 92, M.Z. 24, 4).

9Including ad loc. the Pri Chadash (19), Pri Megadim (S.D. 21, s.v. ayin), Chavas Daas (Chiddushim 2), and Chochmas Adam (42, 17). There are also those who only allow use of these leniency in specific circumstances - see Pischei Teshuva (6), Yad Yehuda (Pih”a 33. Piha”k 37), Ben Ish Chai (Year 2, Bechukosai 12), and Aruch Hashulchan (24).

10Yad Efraim (Y”D 92, 4), Pri Megadim (ibid.), Yad Yehuda (ibid.), Chasam Sofer (Shu”t O.C. 120 s.v. uvchol), Mishmeres Shalom (Y”D 95, M.Z. 15, 1), Aruch Hashulchan (ibid.), Shu”t Yabea Omer (vol. 6, Y”D 10, end 1).

11Shu”t Yabea Omer (vol. 10, 4). His opinion is also cited in HaKashrus B’Halacha (pg.165) and HaKashrus (Ch. 10, footnote 137).

[12]Yalkut Yosef (IV”H vol. 3, 89, 86; and pg. 491 - 492) and Shu”t Ohr Yitzchak (vol. 1, Y”D s.v. madeyach keilim).

[13]Yalkut Yosef (ibid.).

[14]Shu”t Ba’er Moshe (ibid.).

[15]See earlier article titled “The Coca-Cola Kashrus Controversy” for more about this topic.

[16]See footnotes 3 and 4. Additionally, many ofthe authorities who rule leniently in this manner, including Rav Ovadiah Yosef shlit”a, say it is still preferable not to “come into” the sheilah and have to rely upon the hetterim l’chatchila.


Disclaimer: This is not a comprehensive guide, rather a brief summary to raise awareness of the issues. In any real case one should ask a competent Halachic authority.


L'iluy Nishmas the Rosh HaYeshiva - Rav Chonoh Menachem Mendel ben R' Yechezkel Shraga, Rav Yaakov Yeshaya ben R' Boruch Yehuda, and l'zchus for Shira Yaffa bas Rochel Miriam and her children for a yeshua teikef u'miyad!

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