Public bath
From Bahaipedia

A public bath or public bathhouse (in Arabic: حمّام, ḥammám) is a public establishment meant for bathing. They were common throughout the Middle East at the time of Bahá’u’lláh.
In a section of the Kitáb-i-Aqdas which deals with cleanliness, Bahá’u’lláh prohibits His followers from bathing in the public pools of traditional Persian bathhouses:
“ | Immerse yourselves in clean water; it is not permissible to bathe yourselves in water that hath already been used. See that ye approach not the public pools of Persian baths; whoso maketh his way toward such baths will smell their fetid odor ere he entereth therein. Shun them, O people, and be not of those who ignominiously accept such vileness. In truth, they are sinks of foulness and contamination, if ye be of them that apprehend. ... | ” |
— Bahá’u’lláh, Kitáb-i-Aqdas[1] |
The notes on this passage read:
“ | Bahá’u’lláh prohibits the use of the pools found in the traditional public bathhouses of Persia. In these baths it was the custom for many people to wash themselves in the same pool and for the water to be changed at infrequent intervals. Consequently, the water was discolored, befouled and unhygienic, and had a highly offensive stench. | ” |
— Notes on the Kitáb-i-Aqdas[2] |
The Síyáh-Chál, the dungeon in which Bahá’u’lláh was imprisoned in 1852, was originally built as a reservoir and stored water for nearby public baths.