- Peninei Halakha
Any form of pleasurable washing is prohibited on Tisha Be-Av, whether the water is hot or cold. One may not even wash a small part of his body; one may not even dip one finger in water. However, one who became soiled with mud or feces, or has a nosebleed, may wash the soiled area, because his intention is not to take pleasure from washing (sa 554:9). Similarly, one who is changing a child’s diaper may wash the soiled area, even though he will wash his hand in the process. He may even use soap if the filth or odor does not come off with water alone.
If one is preparing food for after the fast or for his children, he may rinse food items and dishes because this is not considered washing for the sake of pleasure. And even though one derives some pleasure every time one washes one’s body, since the main purpose is to remove filth, it is not considered washing for pleasure.
If one perspired excessively, to the point where he is preoccupied and suffering, he may wash the sweaty area because he does not intend to derive pleasure (mb 613:2, sht ad loc. 4). Likewise, one who is very sensitive and cannot settle himself in the morning without washing his face may rinse his face with water. One who accumulates mucus in the corner of his eyes overnight and generally removes it with water may do so on Tisha Be-Av (sa 554:11, mb ad loc. 22).
One may not rinse one’s mouth on Tisha Be-Av. Nevertheless, one who will be very distressed if he does not do so may rinse his mouth and brush his teeth without toothpaste on Tisha Be-Av. On Yom Kippur, however, when there is a Torah obligation to fast, one may not be lenient regarding this issue (see above, 7:5 and n. 6).
A bride within the first thirty days of her marriage may wash her face and apply any ointment she needs to avoid making herself unattractive to her husband (mb 554:29, sht ad loc. 38).
One may take a slightly damp towel and run it across one’s face, hands, and feet, because the prohibition of washing does not apply to such a small amount of moisture. The only condition is that the towel not be so wet that it could moisten one’s hand to the extent that his hand could then moisten something else (Rema 554:14, mb ad loc. 27).