A. The general law:
For pleasure: It is forbidden to wash any part of one’s body [for the sake of pleasure] on Yom Kippur. This applies whether with hot or cold water. Even to stick one’s finger in water is forbidden.
To clean dirt: If one’s hand, leg, or any other part of the body is dirty with mud, feces, or blood due to a nose bleed, it is permitted to wash it with water in order to remove the dirt. Nevertheless, one may only wash the dirty area and not any other part of the limb.
For medical purposes: One who is sick, or contains a medical condition, may bathe for medical purposes. Thus one who returned from a journey with sore feet may place them in water, being that he is not doing so for pleasure purposes.
Children: Children are not to be bathed on Tisha B’av even if they are below the age of Chinuch, unless they are dirty.
May one wash off sweat from his body if he feels dirty?
May a woman after birth wash her body?
A woman which is a few days after birth may wash her body if she feels a need.
If one went to Mikveh right before sunset and his hair is still wet what is he to do?
Some Poskim rule that he should dry his hair in order to prevent benefiting from the water on Yom Kippur.
B. Bathing/washing for the sake of a Mitzvah:
Men immersing in a Mikveh: It is forbidden for a man to immerse in a Mikveh on Yom Kippur even for purposes of Keri.
Mikveh Night on Yom Kippur: A woman whose Mikveh night falls on Yom Kippur, it is forbidden for her to immerse on Yom Kippur, and rather she must postpone it until the next night. [In such a case, she should perform the Chafifa on Erev Yom Kippur and on Motzei Yom Kippur she should again bathe and clean herself, and then immerse.]
Hefsek Taharah: A Hefsek Taharah may be performed on Yom Kippur. Nevertheless, she is to only slightly wash between her thighs for this purpose. It is permitted to use either hot or cold water for this purpose.
Washing hands in the morning: Upon awakening on the morning of Yom Kippur, one only washes his fingers, up until his knuckles, having intention to remove the impurity which they contain [as on these days the impurity does not extend past the fingers]. After drying ones hands with a towel, one should use it to pass over his eyes in order to remove his sleepiness. [At the conclusion of Yom Kippur, prior to saying Kiddush Levana, one washes his [entire] hand three times inconsecutively.]
Washing hands for the blessing of the Kohanim: A Kohen may wash his [entire] hand prior to the priestly blessings, even if he had already washed them in the morning before prayers, as he is not washing for pleasure purposes.
Are Kohanim to wash their hands fully or only until their knuckles in the morning?
Some Poskim rule that Kohanim which will be doing Nesias Kapayim are to wash their entire hands as is regularly done in the morning. Other Poskim rule they are not to wash past the knuckles as is the law by others. [Some write the Rebbe directed a Chassid to wash his hands as usual in the morning as rules the first opinion.]
May a Levi wash his hands prior to washing the Kohen?
If one is not fasting, is he to wash hands as usual [until the wrist] when eating bread on Yom Kippur?
Yes. The hands are to be washed up until the writs as is normally done during the year.
C. Washing after bathroom:
When going to the bathroom before Davening, one may wash his fingers [up until the knuckels, but not the hand] prior to Davening, even if they did not become dirty in the process. When going to the bathroom during other times, one may only wash his fingers, up to his knuckles, if he got them dirty with feces or urine in the process of going to the bathroom. It is advisable to do so in order to say asher yatzar in purity. [If he did not get them dirty in the process, one must nevertheless wipe his hands on an item prior to saying Asher Yatzar, if he touched a normally covered area while using the bathroom.] Based on this, the following is the ruling:
After Maariv: When going to the bathroom after Davening Maariv at night one may only wash his fingers, up to his knuckles, if he got them dirty in the process. It is advisable to do so in order to say asher yatzar in purity.
Before Maariv and during day: If one went to the bathroom before Davening Maariv at night, one may wash his fingers even if they are not dirty. If one used the bathroom on the day of Yom Kippur, he may wash his hands afterwards, after every time he goes, being that the entire day is spent in prayer.
May one wash his entire hands after using the bathroom prior to prayer?
No. One may only wash his hands until his knuckles.
May one wash his fingers three times as usual after using the bathroom before prayer?
May one wash his bottom after using the bathroom?
Yes, one may do so in order to properly remove feces from the area.
If one touched a covered area, or his shoes, may he wash his hands afterwards?
If he is prior to prayer or in the midst of prayer then he may wash his hands up until his knuckle.
D. Washing one’s face upon awakening:
Rinsing mucus from one’s eyes: One may wash mucus from his eyes if he is careful to do so throughout the year.
Rinsing the remainder of the face: One may not wash his face, even if he is a very pampered person, unless he has dirt on his face and desires to wash it off.
E. Cooling oneself off:
Cooling oneself off with a cold bottle: One may not cool himself down with the cold walls of an open bottle of liquid, due to fear of spillage. [If the bottle is closed and its walls are dry without condensation, it is permitted to use it to cool oneself off.]
Cooling oneself off with a wet towel: From the letter of the law it is permitted to soak a cloth in water on Erev Yom Kippur and remove it from the water before Yom Kippur, and let it dry out until it no longer contains [enough water] to get another item wet enough to get something else wet, and he may then wipe his face, hands, and legs with it in order to cool off. Even though he is not doing so in order to remove dirt but rather to receive pleasure, nevertheless it is permitted from the letter of the law [to do so], being that [the towel] is dry from the water, as is explained in chapter 554 regarding Tisha B’av. Nevertheless, on Yom Kippur one is to be stringent being that if one were to clean himself with a cloth that was not dried from its water, it would contain a Biblical prohibition due to squeezing. Therefore, one is to be stringent even by a [cloth which was] dry from the water which was on it from before Yom Kippur, due to a decree that perhaps it will not dry well and one will clean with it and come to squeeze.
Summary: One should not cool himself down with a dry towel that was wet before Yom Kippur. Needless to say, a wet towel is forbidden to use.
F. Rinsing the mouth:
It is forbidden to rinse one’s mouth on Yom Kippur. This applies even if one will be using less than a Revius of water. [This applies even if it is causing one great discomfort, he may not be lenient to rinse his mouth on Yom Kippur.]
 Admur 613/1; Michaber 554/7 regarding Tisha B’av
 Admur 613/1; M”B 554/19 regarding Tisha B’av
 Admur 613/1; Michaber 554/9 regarding Tisha B’av
 The reason: As the bathing prohibition only applies towards bathing for pleasure. [Admur ibid; M”B 554/19]
 Admur 613/7
 See Admur 616/3-4
 Admur 614/1; M”A 614/1; Kaf Hachaim 554/45
Opinion of Admur: In 614/1, Admur differentiates between the prohibitions of anointing and washing, saying that by anointing it is prohibited even for non-pleasure purposes, such as for the purpose of removing sweat, while bathing is only prohibited for pleasure purposes. From this it is strongly implied that one is allowed to wash himself in order to remove sweat, as this does not involve a pleasure purpose. Thus, seemingly sweat is considered like dirt.
 Taz 613/1; Yifei Laleiv 2/4; Mateh Efraim; M”B; Nitei Gavriel 70/5
 Aruch Hashulchan 613/9
 Lehoros Nasan 2/46
 Admur 613/19; See Piskeiy Teshuvos 613/6
 Admur 613/18
 How can we allow her to transgress a Biblical prohibition of bathing on Yom Kippur just in order to beautify herself? Perhaps there is no Biblical prohibition involved here being that she has no intention for doing it for pleasure and its only being done to find favor in the eyes of her husband, and in such a case the sages were not stringent to prohibit it due to a mere suspicion. Alternatively, it is permitted being that finding favor in her husband’s eyes is considered a Mitzvah.
 Admur 613/20
 The reason: As since she will not be having marital relations, her immersion does not involve a Mitzvah at all, as immersing at the proper time is only a Mitzvah due to the marital relations. [Admur ibid]
 See Rama Y.D. 199/4 regarding Motzei Shabbos, and the same applies to Motzei Yom Kippur
 Admur 613/21
 The reason: As this is being done for the sake of a Mitzvah, to hasten her going to Mikveh and having Tashmish, and the prohibition against bathing on Yom Kippur only applies towards bathing for the sake of pleasure. [Admur ibid]
 Admur 613/2; Michaber 554/10 regarding Tisha B’av
Does this ruling apply even according to the Siddur? This ruling is going in accordance to the ruling of the Mahadurah Kama 4/7 that there is no obligation to wash past the fingers. This is opposed to the ruling in the Siddur that one must wash up until the wrist [and thus there is room to say that according to the Siddur even on these days one should wash until his wrist], nevertheless the custom according to all on Yom Kippur and Tisha B’av is not to wash past the fingers, and so ruled the Previous Rebbe. [Rebbe in Shaareiy Halacha Uminhag Vol. 2 page 181]
 Rebbe in Shaareiy Halacha Uminhag Vol. 2 page 182; Ketzos Hashulchan 2 footnote 10
The reason: The reason for this is because the Mekubalim explain that on Yom Kippur the spirit of impurity does not have much power. While on Tisha B’av since there is not much purity on that day, therefore it does not seek much nurture of holiness from the hands, and thus only dissipates to the fingers. [Rebbe ibid] [Alternatively] on Tisha B’av, the entire day belongs to the impure side, and thus the impurity does not care to nurture from such a minute amount of holiness found past the fingers. [Ketzos Hashulchan ibid; brought also in Kaf Hachaim 4/14 and Ben Ish Chay Toldos 2]
Why don’t we wash the entire hand as does a Kohen? The Ketzos Hashulchan ibid asks that although from the impurity perspective there may not be a need to wash past ones fingers on these days, nevertheless being that another [main-Kama] reason for the morning washing is to prepare for prayer/serving G-d like a Kohen, therefore there should still be an obligation to wash the entire hand, as a Kohen must wash his entire hand prior to service. He concludes with a Tzaruch Iyun. [To note however that this question is not only with regards to Yom Kippur, as it should also be asked on the ruling of Kama 4/7 that the everyday washing is only required until the knuckles. To also note from the Siddur that the only reason why Admur require the washing until the wrist is, as he states, “because the impurity dissipates until the wrist”. Thus there is no opinion that says washing the entire hand is required due to exemplifying a Kohen.]
 Lit. “Chevley Sheyna”. Evidently this is done in order to be able to say the morning blessing of “Hamavir Shayna” with having received its pleasure beforehand, as explained in “The Laws of The Morning Blessings” chapter 56.
 Rebbe in Shaareiy Halacha Uminhag Vol. 2 page 183
 Admur 613/6
 Kitzur SHU”A 133/4; M”B 613/7; Ketzos Hashulchan 2/10; Luach Kolel Chabad of Grach Naah; Likkutei Sichos 9/386; Yagdil Torah 1 page 318; Hiskashrus 889
Other opinions: Some Poskim rule one is to wash the hands only until the knuckles. [see Misgeres Hashulchan 133/4]
Ruling of Admur in Shulchan Aruch: See Yagdil Torah 1 page 318 in which Rav Bistritzky explains that according to Admur in Shulchan Aruch it is implied that one only needs to wash until his knuckles. Nonetheless, as he concludes there, the Rebbe said to wash entire hand, and so rules Grach Naah in Luach Kolel Chabad and in Ketzos Hashulchan ibid based on Admur ibid.
 Kitzur SH”A 133/4
 The reason: This is done in order to avoid requiring a second blessing when washing for Nesias Kapayim. [ibid]
 Misgeres Hashulchan 133/3 argues on the Kitzur Shulchan Aruch.
 Otzer p. 217
 Mateh Efraim 621/17
 Shevach Hamoadim p. 50 in name of Maharil
 Kaf Hachaim 554/53 in name of Tosefes Chaim 155/10; Shevet Halevi 8/139; SSH”K 39/31; Lehoros Nasan 2/42; Shraga Hameir 5/45; Piskeiy Teshuvos 613/2; 618/15
 Admur 613/4-5; see M“B 554/21
 See 7/2; 92/5-7; 164/2; Seder Birchas Hanehnin 13/17
 Admur 613/4-5; Michaber 613/3; M”B 613/6; Piskeiy Teshuvos 613/2
 Mateh Efraim 613 in Alef Lamateh 7
 Nitei Gavriel 70/2; Piskeiy Teshuvos 613/3; Shearim Hametzuyanim 133/2; Shevet Hakehasi 4/165
 Piskeiy Teshuvos 613/2
 Admur 613/3
 Although from the letter of the law one who is pampered may wash his face, nevertheless the custom is not to do so. [ibid]
 Admur 614/28
 Admur 613/16; Rama 613/9
 The reason: This is prohibited even on Shabbos due to suspicion that one may come to squeeze. The same applies if the towel is now dry but was wet Erev Shabbos that it is forbidden to use on Shabbos because of suspicion that the towel will not be fully dry and one will come to squeeze.
 Admur 613/7; See Piskeiy Teshuvos 613/5; Michaber 567/1 that one may not taste anything on Tisha B’av, even if he will spit out and 567/3 “One who is accustomed to rinse his mouth, it is improper-not Kosher- to do so on a public fast day” based on Terumos Hadeshen 158 regarding the prohibition to taste foods on a fast; M”A 567/6; Drashos Maharil, brought in Darkei Moshe 567/1 and Elya Raba 567/5 and Kaf Hachaim 567/14; Mamar Mordechai 567/2; Levush 567; Nehar Shalom 567/1; Bigdei Yesha 567/6; Kaf Hachaim 567/13; Chayeh Adam 132/20; Ketzos Hashulchan 2 footnote 25 in name of Ateres Zikeinim; Sefer Haminhagim p. 4 [English]
Stringency or prohibition? It is implied from the Michaber ibid that there is no prohibition from the letter of the law involved in rinsing the mouth even on Yom Kippur, being one has no intent to swallow the liquid and it is merely water. [P”M 567 A”A 6]
 The reason: As one may come to swallow the water. [Mamar Mordechai 567/2; Levush 567, brought in P”M ibid]
 Michaber 567/1
 Chayeh Adam 132/20; M”B 567/11; Kaf Hachaim 567/14