My mother-in-law has a non-Jewish helper. They will both be residing at my sister-in-law during Pesach, this year.
The helper brings her own non-kosher (chametz) food with her during Pesach. I have several questions about how she might store it during the week:
1 – Can she store it in the regular Pesach fridge that the family uses if her food is placed in a specific section of the fridge and it is marked so that it is clear that the food is hers and no one will accidentally use it? How is this scenario different from buying Pesach food from the store where chometz & Pesach food are stored in the same fridge?
2 – If the section or use of the fridge is “rented” to her before Pesach, does this change the scenario?
3 – There is an extra fridge in the basement filled with all chametz stuff that the family doesn’t use during Pesach. (The fridge contents have been sold, of course.) Can she use this fridge and is this the best scenario?
It is not permitted to keep chametz in the house in a place where the chametz will be seen and it in arm’s reach. According to the Gemara a mechitza (a partition) must separate between the house and the chametz.
The chametz, providing of course it belongs to a non-Jew, must therefore be kept completely separately, in a place that is marked as belonging to the non-Jew. This is similar to the law concerning chametz that is sold to a non-Jew, which must be kept separate, such as in a sealed closet marked as chametz.
Keeping the chametz in the regular pesach fridge is not a good option, and this is different from stores in which the chametz goods are entirely covered over and and not used for the duration of Pesach. Your option of using the extra fridge is the best option under the circumstances.
See Shulchan Aruch 440:2 and commentaries; see also Siddur Pesach Kehilchaso 17.