Post History

As I understand it, the Tevilah requirement comes in when:

* A vessel for use with preparing or eating food is manufactured by a non-Jew
* A vessel for use with preparing or eating food is owned by a non-Jew

Manufactured by a Jew, sold to a non-Jew, sold to a Jew - requires Tevilah

Manufactured by a Jew, sold to a Jew, sold to another Jew - does not require Tevilah

Manufactured by a Jew, sold to a Jew, given to a non-Jew, given to a Jew - requires Tevilah

and so on. An interesting twist is that re-manufacturing by a Jew (possible example: disassembling an appliance beyond the normal amount done for cleaning and then reassembling it) also counts - i.e., then it is considered manufactured by a Jew and does not need Tevilah.

While there is a similarity to Kashrus, this is independent. Classic example is that if you have vessels that need to be Toveled and don't have time to do so before Shabbos (or other situations, but Shabbos is the usual example) you can give them to a non-Jewish neighbor and then borrow them back. You now have Kosher vessels (never actually used by the non-Jew) that are owned by a non-Jew and non-Jews don't need to (in fact, *can't*) do Tevilas Keilim while they own the vessels, so they are perfectly fine to use. A vessel that was purchased (or a gift or inherited) from a non-observant Jew may require *both* Kashering and Tevilah before use. A non-Kosher vessel might be perfectly fine to use from a Kashrus standpoint for certain uses (e.g., for use with a cold beverage) yet still need Tevilah because it is owned by a Jew and was at some point owned by a non-Jew.

As far as buying vessels from a Jew where they were manufactured by a non-Jew or previously owned by a non-Jew, if the Jew you buy them from is a reseller and not an ordinary consumer then not only must you assume they have not been Toveled, but they are actually not *allowed* to "pre-Tovel" them for you. They could Tovel them *after* you purchase them, as a service, and there are stores which have a Mikvah on premises so that customers can Tovel their vessels before they go home. On the other hand, if a Kosher restaurant or caterer that is owned by a Jew (and therefore would have had to Tovel all their vessels) sells off their used vessels, they would *not* require Tevilah.