There is an article from Rabbi Michael J. Broyde on showering on Yom Tov. The usual rules about not making halachic decisions based on what you read on an internet website apply. But I feel that there is a tremendous lack of up-to-date knowledge on the subject. To rectify that you can read Broyde’s article, complete with 89 footnotes, or you could just continue reading this.
I posit that it is permitted to shower with hot water on Yom Tov (not just on Yom tov sheni shel galuyot) one’s entire body (not just one limb at a time).
Why this is so can be simplified in one catchy line: showering is shaveh lechol nefesh (Benefit to all people.)
To give slightly more detail. The Torah forbids work to be done on Yom Tov (like Shabbos) with one glaring exception. Exodus 12:16: “On the first day you shall have a holy assembly, and another holy assembly on the seventh day; no work at all shall be done on them, except what must be eaten by every person, that alone may be prepared by you.” The Mishnah, in Beitzah 36b says: “There is no difference between [the laws of] holidays and Shabbat except only for ochel nefesh [certain types of food preparation which, though forbidden on Shabbat, are permitted on festivals].” The Talmud, in Ketubot 7a, extends this leniency (using the expansionary power of “mitoch”) to anything personal that is needed for the Yom Tov and, significantly, qualifies as shaveh lechol nefesh. Shaveh lechol nefesh, simply put, means that most people do so, or would like to do so, regularly. The gemara uses the example of slaughtering a deer that one finds as something that is shaveh lechol nefesh, despite the fact that most people don’t have regular access to deer meat. It is enough that they would, if they could.
In the West, showering daily is shaveh lechol nefesh, no doubt. Therefore it is permitted to shower with hot water on Yom Tov.
Indubitably, this has not always been the case. For most of humanity, for most of history, daily bathing was not a reality. (King Louis XIV, the great and famous Sun King, bathed as little as two times in the entire 76 years of his life.) It should be no surprise then, that bathing daily was not considered shaveh lechol nefesh. As early as the Mishnah, tothe times of Tosafos (Tosafos Beitzah 21b s.v. lo yichamem) and Shulchan Aruch (OC 511:2), only the washing of the face, hands and feet was permitted on Yom Tov, but not the full body. That was considered the conventional hygienic thing to do and was thus shaveh lechol nefesh.
But times have changed. Today shaveh lechol nefesh is showering one’s entire body with hot water daily, or close to daily. But is shaveh lechol nefesh not immutable? No. Is it dependent on local conditions? Yes.
Magen Avraham (OC 511:5) states that, in contradistinction to the Rema who permits bathing a baby on Yom Tov, it is forbidden to bathe a baby on Yom Tov. Because, he writes, nowadays we don’t bathe babies every day. The Mishnah Berurah (Biur Halacha 511 s.v. yadav) suggests that times have changed and that nowadays it is not shaveh lechol nefesh to wash one’s feet because we don’t walk around without shoes. Rabbi Moshe Feinstein (Iggerot Moshe OC 5:34) speaks about smoking on Yom Tov and its possible change of status in regards to shaveh lechol nefesh. It could thus be said with high degree of confidence that shaveh lechol nefesh is dependent on local conditions and is not immutable.
One last thing, while showering on Yom Tov does qualify as shaveh lechol nefesh, smoking, most probably, does not. In the US only one out of six adults smoke, and a plurality of those that do smoke consider it to be a nasty and dangerous addiction. To me, that does not sound like something that is shaveh lechol nefesh.
Showering On Yom Tov (PDF)