Is there any heter to use hot water on shabbos - for say washing dishes, or for bathing children (not addressing issues of drying hair etc)? Does leaving a faucet of hot water running before shabbos help in any way? If, so, how?
There are at least 2 aspects involved:
How to get hold of hot water on Shabbat without desecrating the Shabbat. This is a technical question.
- You could leave the tap on, assuming the water remains how for hours on end.
- You could invest in a Shabbat-hot-water system whereby no cold water enters the system on Shabbat, for example.
What can you do with hot water on Shabbat?
- You could use it to cook items that won't have a Bishul issue.
- You could use it to wash dishes assuming you need them again on Shabbat and you don;t have a Bishul issue (like washing off fresh lettuce in boiling water, which may possibly cook it.)
- You could use it to wash, but only less than half your body, as documented in the Kitzur Shulchan Aruch at 86:1 סימן פו - דין רחיצה
אָסוּר לִרְחוֹץ כָּל גּוּפוֹ אוֹ אֲפִלּוּ רֹב גּוּפוֹ בְּמַיִם חַמִּים, אֲפִלּוּ הוּחֲמוּ בְּעֶרֶב שַׁבָּת. וַאֲפִלּוּ לִרְחוֹץ שֶׁלֹּא בְּפַעַם אַחַת, אֶלָּא אֵבֶר אֵבֶר, אָסוּר בְּרֹב גּוּפוֹ. וַאֲפִלּוּ לִכָּנֵס לַמֶּרְחָץ רַק לְהַזִּיעַ, גַּם כֵּן אָסוּר. אֲבָל מֻתָּר לִרְחוֹץ פָּנָיו יָדָיו וְרַגְלָיו בְּחַמִּין שֶׁהוּחֲמוּ בְּעֶרֶב שַׁבָּת