806. Bathing on Shabbos

Shabbos 22:2

The Sages prohibited entering a bathhouse on Shabbos because the attendants used to heat the water on Shabbos and tell the customers that it was heated before Shabbos. For this reason, they enacted that one should not enter a bathhouse at all on Shabbos, not even to sit in the steam. They likewise enacted that one may not rinse his entire body with hot water on Shabbos, even if the water was heated beforehand. One may, however, wash his face, hands and feet. All of this only applies to water that was heated with fire; one may wash his entire body in hot springs like those in Tiberias. One is not permitted to bathe in hot springs that are in caves because the cave gets filled with hot air and one sweats in the manner of a bathhouse.

Shabbos 22:3

A person is permitted to warm himself in front of a fire and then go wash his entire body in cold water. One may not, however, wash his body in cold water and then go warm himself by the fire. This warms the water on his body so it is as if he washed in warm water. If one causes a stream of cold water to pass through hot water - even water from the Tiberias hot springs - the water is treated as if it was heated by fire and one may neither wash in it nor drink it.