Rav Chaim Weg Question: We have stated that the ikkur mitzvah of limud haTorah is…
Rav Yosef Kushner
Question: If someone owns an apartment building with non-Jewish tenants who will have chametz in their apartments on Pesach, is that a concern?
Answer: Chametz that belongs to a non-Jew is not a problem at all. Technically, even if a non-Jew would bring chametz that he owns into a Jew’s home, the Jew would not be transgressing anything, as it is not his chametz. It is definitely true that chametz owned by a non-Jew in his apartment would be no problem.
The question would be what to do about chametz discarded by a non-Jew inside his apartment. Once the non-Jew throws chametz into the garbage can, he reneges his ownership and it becomes ownerless. The halacha is that it is forbidden for a Jew to have ownerless chametz on his property on Pesach. Thus, we can ask if this chametz is a problem.
The answer would be that chametz inside apartments that are rented out to non-Jews are usually not a problem, even after the non-Jew removes his ownership. This is because according to the way leases are structured today, the renter gains control of the apartment, and is considered to be the temporary owner; therefore, it is not considered to be the landlord’s property, and he need not be concerned about ownerless chametz that is in it.