Dear Rabbonim Shlita
The Halocha is that it is forbidden to bathe or shower during the 9 days. I understand that the basic allowance is to wash hands, feet and face in warm water, and only in certain cases of sweatiness or for health reasons, may one wash ones entire body in hot water with soap.
However, this isur was given to a generation that bathed exclusively at the Beis Hamerchatz (bathhouse), and far less frequently than we do today.
Also, we pasken by Yom Tov that one may only heat water to wash ones hands, face and feet because that is called shaveh lekol nefesh (something universal).
But in today’s generation most people bath or shower at least once a day and it is a societal norm to do so with hot water and soap.
Therefore, can the the isur on bathing be treated differently today?
Admittedly if the prohibition is in stone than there’s no question, but since we anyway make exceptions for pregnant woman/health reasons and we consider remving sweat to be OK, then can we not be more lenient than hands, face, feet in warm water?
In giving shiurim to baal habatim arguably one of the most difficult halocha that people battle with, is this one, and even in Yeshiva, some boys had great difficulty with this.
In light of the rulings of poskim, it is difficult to give a blanket heter (permission) in this matter (for for the Nine Days and for Yom Tov).
For the Nine Days, there is no reason to think that the halachah should undergo a change from its original enactment, which permits sombody who requires a shower to take one. Please see here and here for more details (note that the shower doesn’t have to be cold, but should not be “comfortably warm.”
Today, the number of people who “require a shower” is clearly greater than in the past, but this does not require an adjustment of the original halachah.
The question of Yom Tov is more complicated (see below). Under extenuating circumstances (such as three days of Yom Tov/Shabbos in the summer, which can happen for Rosh Hashanah, or two days for those who suffer), and where a cool shower is not a viable option, there is some room for leniency.
Somebody who takes a shower (cold or warm) on Yom Tov must be careful to ensure that he does not run into related prohibitions. He may not dry his hair (but can place a towel over the hair, without pressing), and must ensure that no fire will be lit or other system activated when the faucet it turned on.
Sources (for question of Yom Tov):
As the question rightly notes, the idea of showering daily has become fairly universal, certainly in summer days, and the times when many bathed once a month or once a week are behind us.
This should seemingly be reflected in the halachah of bathing on Yom Tov with hot water; bathing is no longer “eino shaveh le-chol nefesh,” and there seems to be little reason why it should be prohibited today. Indeed, I have seen that Rav Yitzchak Abadi (Or Yitzchak, Orach Chaim 210) writes that it is permitted nowadays to heat water on Yom Tov for purposes of bathing, for this reason.
However, some poskim write that the halachah remains unchanged. The Be’er Moshe (8:159) is extremely sharp in this, and writes that he does not even want to consider the possibility of changing the halachah based on changes in social norms of washing, and he goes on to write that it is “entirely simple” that the prohibition remains in place.
Although he does not explain his reasoning, it would seem that he sees the prohibition against washing as a rabbinic takanah (enactment), which we cannot permit based on social changes.
It is hard to accept this line of reasoning. We see from the Mishnah Berurah (511, in the biur halachah) that the halachah of smoking on Yom Tov changes based on social norms, and there is no apparent reason to think that the halachah of bathing shouldn’t change, too. The specific decree of a merchatz (bathhouse) will not, apparently, apply to a shower in one’s private home.
Indeed, when Rav Chaim Kanievsky was asked this question, he did not respond that the halachah cannot change, but wrote back that even today, bathing is not shaveh le-kol nefesh. This does not seem to be the case for society in general, where daily showering, certainly after two days during hot weather, is fairly universal.
Yet, although poskim were aware of the possibility, we do not find that most authorities are ready to be lenient. Shemiras Shabbos Kehilchasah (Chap. 14, note 21) brings up the point at length, and concludes with a tzarich iyun (requires further elucidation), whereas in the main section he rules in line with the basic Talmudic law. Rav Elyashiv, shlita, is likewise quoted in Shut Avnei Yashfei (3:55) as being stringent on this question.
It is possible that poskim do not wish to be lenient in this regard, for fear that leniency will lead to other pitfalls, such as in drying one’s hair, using soap, and so on. This is similar to the stringency mentioned by the Mishnah Berurah (326:21) concerning bathing in cold water on Shabbos.
Therefore, based on the rulings of poskim, it is hard to issue a blanket heter (leniency) on this matter. However, for extenuating circumstances, there is room to act leniently.