Ask the Rov: After my Shabbos meal, I am always left with a huge pile of dirty dishes to clean. Can I allow my cleaning lady to wash them with hot water or use the dishwasher on Shabbos?
By Rabbi Chaim Hillel Raskin, Rov of Anash in Petach Tikva
Dishes may be washed on Shabbos with cold water if they are needed on Shabbos. If a cleaning lady on her own washes all the dishes so she won’t have to stay until after Shabbos, one need not stop her. However, one may not explicitly instruct her to do so unless there is a great need. (See issue 535 regarding using hot water on yom tov.)
In the standard hot water faucet, there are two issues of (a) causing cold water to enter the boiler and cook, and (b) this may trigger the boiler to ignite. These concerns do not apply to asking a non-Jew to use the hot water, since by melacha done by a non-Jew, unintended outcomes are not of consequence. Thus, one may even directly instruct the cleaning lady to use hot water for the dishes.
If the faucet works by directly igniting a tankless boiler, one may not instruct the cleaner to use it. However, if she uses is it on her own initiative for her own convenience, one needn’t stop her, unless she knows that the family is particular to use hot water for washing dishes, in which case asking her to wash the dishes is equivalent to asking her to use the hot water.
What if the cleaning lady wants to make her job easier by using the dishwasher? While it would seem to follow the same principles, contemporary poskim prohibit it, since it generates some noise (avsha milsa) making it noticeable that melacha was done without indication who turned it on.
Additionally, having a machine do work on Shabbos is disgraceful to the sanctity Shabbos (zilzul Shabbos), which likewise prohibits having it start on a timer. For the same reason, one may not allow a cleaning lady to vacuum, even if she is doing it to spare her effort in cleaning up manually.
It is permitted to place dirty dishes in a dishwasher on Shabbos, to store them out of the way. However, one may not arrange them in a specific order, since that is considered preparing for after Shabbos and it may also run into issues of borer.
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