The question was asked in regards to the laws of Borer, which is the prohibition of selecting on Shabbat. In most households, a small strainer is found at the drain in the kitchen sink, and its purpose is to separate out food particles in order to prevent the food particles from clogging the drain. So there is a question that we need to address in regards to Shabbat and sink strainers. Is it considered a transgression in the laws of Borer when spilling out vegetable soup or other lqiuidy items into the sink? The strainer is separating the food particles from the liquid. Seemingly this is a transgression because a Keli (vessel) is being used to select, and using a vessel to select is forbidden on Shabbat from the Torah.
This question was addressed by Rabbi Moshe HaLevi in his book ‘Menuhat A’Hava’, and it is also brought down in the book ‘Shemirat Shabbat Kilchita’ written by Rabbi Yehoshua Neuwirth. Both agree that it is permissible to have the strainer in the drain of the sink, and it is not a transgression of Borer. They explain that one is not selecting good from bad or bad from good in this case, and therefore Borer does not apply. A person is really discarding all the contents of the food, both liquid and solids, and as such it is all considered bad (Pisolet). The strainer is separating the contents in order to prevent clogging in the pipes, but that is not a violation of Borer. The laws of Borer only apply when selecting good content from bad, or bad from good. In this case, all is bad, hence the laws of Borer are not applicable.
Halacha Lema’ase, the use of a sink drain strainer is not a transgression of the laws of Borer.
