Q. I moved lately to a building with over seventy tenants, some Jewish some not. I’m wondering if I can use the hot water during Shabbos if I keep it lower than Yad Soledes (40 Centigrade), just to take off the chill of cold water. Since the water comes out from the hot and cold taps in a single spout, the cold water never really warms up enough to create Bishul.
I understand that in a single house, where the opening of the hot water would immediately causes cold water to enter the hot water boiler and one would transgress on bishul. But in such a large building water is constantly used, so it is unlikely that the use of water in one unit, would make any difference. Is it permitted? Why not?
A. Using a single spout does not avoid the Bishul or cooking prohibition of the cold water being heated as it encounters the water emanating from the hot pipe that is Yad Soledes. It only cools down after being in contact with the cold water and having already transgressed on Bishul.
Horav Shlomo Miller’s Shlit’a opinion is that the fact that one is in a very large building, does not avoid that a likely few or even a single small drop would be added to the large boiler when you open your tap and that is enough to transgress on the prohibition. (See next question).
Rabbi A. Bartfeld as revised by Horav Shlomo Miller, Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a