Bathing in Hot Water on Shabbos

Washing or Bathing in Water Heated Before Shabbos

One may wash part of one’s body with water that was heated up before Shabbos, such as one’s hands, face, or other limbs of one’s body (this is assuming that no cold water will be heated up as a result of one using the existing hot water).
- However, one may not do so to the point of washing the majority of one’s body, even if one only does one limb at a time; Chazal forbad this lest one come to heat up water on Shabbos.
- This is true whether one is immersing one’s body into warm water, or pouring the water over oneself, such as in a shower (SA, R 326:1, MB 1-2, SSK 14:1).

Warm: For this prohibition (of washing the majority of one’s body in water heated up before Shabbos) to apply, the water need not be hot to the point of yad soledes bo (the temperature where one’s hand would recoil when touching the water) – 45 degrees Celsius (c110 Faranheit) – which is the relevant temperature in relation to the melacha of bishul (cooking); it suffices that the water has been heated up and is considered by people to be warm. Going forward we will use ‘warm’ and ‘hot’ interchangeably.
Lukewarm: However, if the water is merely lukewarm it has the halachos of cold water.
Contemporary poskim debate exactly when water is considered ‘warm’ versus ‘lukewarm’ with some suggesting the distinction is whether the water is warmer or colder than body temperature; SSK rules that water is considered lukewarm if one does not have a sense that the water feels warm. (MB 326:7, SSK 14:11, fn3, Dirshu 326:5, PT 326:1)

Given the prohibition outlined above (of washing in warm water on Shabbos), the poskim heavily debated whether it is permissible to immerse in a warm mikvah on Shabbos.
Women: The accepted practice nowadays is to be lenient for women who go to mikvah on Friday night to immerse in a warm mikvah, though they should not linger in the water beyond what is necessary for their tevilah.
Men: A man who wishes to immerse in the mikvah for Tevilas Ezra or simply for extra kedusha should consult a Rav for guidance about whether he may do so in warm water, or whether he should seek to find a mikvah which is merely lukewarm, or perhaps even defer the tevilah until after Shabbos, given the custom we will outline in the coming pages not to wash one’s whole body even in cold water on Shabbos (MB 326:7, 24, SHT 5, SSK 15 fn4, PT 326:5).

Significant Distress: One who washes in warm water daily and is significantly distressed (known as ‘mitztaer’) when unable to do so on Shabbos, may wash their entire body in water which was heated before Shabbos (so long as they do so in a manner that will not cause cold water to be heated up in Shabbos(; in cases of significant distress, Chazal waived this prohibition (BHL 326:1 D”H BeMayim, SSK 14:1).
- Nowadays, given we bH have easy access to hot water before and after Shabbos, this exception should rarely apply.
Sick people and babies: This prohibition is also waived in cases where it is necessary to wash a person who is sick, or a baby who is normally washed daily, so long as the water was heated up before Shabbos and cold water won’t be heated up as a result (SSK 14:1).

If water was heated up in a prohibited manner on Shabbos, for example by placing it on the stove until it reached yad soledes bo (45 degrees celsius, c110 farenheit, thus violating the melacha of ‘bishul’, cooking), one may not wash in that water at all (SA 326:3, MB 15, SSK 14:2).

Even if water was actively warmed up in a permitted manner, such as if a Jew put water near a flame in a way where it would not reach yad soledes bo (so there is no concern of bishul) and so it only became lukewarm, or if a non-Jew heated up the water for someone who is ill, it remains prohibited to wash any part of one’s body with this water (note the stringency on lukewarm water versus lukewarm water heated before Shabbos) (MB 326:17, SSK 14:2).

If the water was heated up on Shabbos but without any action being performed on it on Shabbos to heat it, for example if one had put cold water on a covered stove just prior to Shabbos, or if the water was heated up in a dud-shemesh (solar heated water tank, see below re if more water will be drawn into it), the parameters of washing in this water are the same as those for washing in water which was heated before Shabbos, as outlined in the first section above (in brief, one may wash part, but not the majority, of one’s body with it) (SSK 14:3).

if one has taken hot water from a saucepan, an urn etc which was heated up before Shabbos to wash the minority of one’s body and one wishes to add cold water to cool it down somewhat, one must ensure to avoid ‘cooking’ the cold water due to the melacha of bishul. One has the following options:
- Pour the hot water from the urn or saucepan into another vessel, known as a ‘kli sheni’; there is no prohibition of cooking water in a kli sheni, so cold water may then be added after the hot water has been poured in without restriction.
- Pour the hot water into another utensil already containing cold water (this is called ‘iruy kli rishon’, pouring from the first utensil), ensuring that one pours sufficiently little hot water that the resultant mixture does not reach the heat of yad soledes bo (45 celsius, c110 farenheit).
- (Relevant only by a saucepan etc, not an urn) Remove the saucepan from the fire, and in one go, pour in sufficient cold water that the resultant mixture is below the heat of yad soledes bo; one may not pour it in slowly as the initial cold water will be heated above Yad soledes Bo (SSK 14:5).

We have emphasised in our discussion about washing in hot water over Shabbos that in the cases when one may wash oneself with hot water on Shabbos, one may not do so in a manner which will lead to cold water being heated up, as heating up water is forbidden due to the melacha of ‘bishul’, cooking.
This issue typically arises when drawing hot water from a hot water system like a boiler, when drawing out hot water will normally lead to new cold water being drawn in and heated up (see the separate page in this section on hot water systems).
Depending on the type of hot water system, there may be solutions to allow one to draw hot water out of it on Shabbos, one should consult one’s Rav for guidance based on the type of hot water system one has.