Question: We were invited to a family member’s house who does not keep kashrus properly but have gone out of their way to buy us kosher food. They have even bought us new plates to eat from, though they haven’t tovelled them. What can we do?
Answer: While there are some rishonim that allow one to use dishes that have not yet been tovelled (See Raavya, Pesachim 464; Hagaos Maimonos, Maacholos Assuros 17:6), the Rema (YD 120:8) and other rishonim (Issur Vehetter 58:85; Rokeach 481) write that one mustn’t use such dishes. Nonetheless, the Yeshuos Yaakov (120:1) and Mishna Berura (Biur Halacha 323:7) write that this prohibition is miderabanan.
The Rema (YD 120:16) writes that the lack of tevila does not render the food forbidden to eat. The food should be transferred to another dish before eating, though.
The Shulchan Aruch (YD 120:8) writes that if one borrowed a dish that hadn’t been tovelled from another Jewish person, they are obligated to tovel it, unless they bought it for non-food purposes.
Thus, R’ Moshe Feinstein (Igros Moshe YD 3:22) writes that if one is eating in a Jewish owned hotel that hasn’t tovelled its dishes, one can only eat something solid that can be removed off the plate. One would not be able to have soup, though, etc. (See Rivevos Ephraim 5:480:1:12).
R’ Yitzchak Yaakov Weiss (Minchas Yitzchak 1:44), R’ Shlomo Zalman Auerbach (Minchas Shlomo 2:66:14) and R’ Ovadia Yosef (Yechave Daas 4:44) write, however, that one running a food business is comparable to one who buys a knife for non-food purposes. Thus, they justify the practice of many establishments who don’t tovel their catering dishes. Likewise, one may eat at such places even if one knows that the dishes haven’t been tovelled (See Minchas Asher 3:55:4). This wouldn’t necessarily apply to eating at one’s friend’s house, however.
R’ Zvi Cohen (Tevilas Kelim 3:n19) quotes R’ Yitzchok Isaac Liebes (Beis Avi 116) who addresses a similar scenario. He writes that porcelain and glass dishes only require tevila miderabanan. In fact, according to the Yaavetz (Sheilas Yavetz 1:67) porcelain dishes don’t require tevila at all (See Aruch Hashulchan YD 120:29).
Additionally, guests aren’t in the same category as one who hires or borrows a dish. As the Rema writes that the food itself would not be prohibited even for the host (if it was transferred to a different container), there is no reason to prohibit it for the guest. Thus, he concludes that one may eat on non-tovelled dishes if absolutely necessary.In conclusion, it would certainly be okay to take a biscuit, etc. from such a plate. Under such circumstances, you could eat normally from these plates, though you shouldn’t rely on this elsewhere if you can easily use disposable dishes, etc.