Ritu­al baths are part of the Jew­ish tra­di­tion. Baths were already dis­covered dur­ing ex­cav­a­tions in an­tiquity. An­tique Mik­vaot can be seen i.e. on Mas­ada and in Korazin in Is­rael.

A par­tial warm­ing of the water in a Mik­vehAccumulation of water
מקוה which for in­stance is fed by a well by scoop­ing warm water to it is gen­er­ally pos­sible. In the course of cen­tur­ies dif­fer­ent tech­niques have been de­veloped. Mod­ern Mikwaot from the middle of the 20th cen­tury mostly offer warm water apart from hy­gien­ic stand­ards such as tiled basins.

 

For the ritu­al pur­ityTahor
טהור ­Tahor
טהור of a Jew­ish com­munity a Mikwe is es­sen­tial. There­fore, a ritu­al bath is more im­port­ant than the con­struc­tion of a syn­agogue. This is what it says in the Talmud (Megilla 27a), this is what the Halacha, the Jew­ish re­li­gious law (Igrot Moshe, Choschen Mis­chpat 1,42), provides for. 

The mik­veh serves the at­tain­ment of ritu­al pur­ity by im­mer­sion in liv­ing waterWell
מַעֲיָן. How can water be alive? Liv­ing water is ground­wa­ter, spring water, rain­wa­ter, melt­water, river water. Lakes with stag­nant water are not ad­equate. If pos­sible, one shall not use rivers as mik­vaot (Schulchan Aruch, Jore Dea 201,2). This was dis­cussed again es­pe­cially after the Cru­sades and the forced bap­tisms in rivers. 

The im­mer­sion pool in a mik­veh should at best con­tain about 1000 litres of water. Be­fore vis­it­ing a mik­veh, it is im­port­ant to clean the body thor­oughly. The pure water shall not be con­tam­in­ated by any­thing for­eign to the body: not by make-up, jew­ellery, pros­theses.
Pray­ers are said be­fore, dur­ing and after the three im­mer­sions.

A Mik­veh is mainly vis­ited by women. As re­li­gious jew­ish women, they im­merse into the water be­fore the wed­ding, on the sev­enth day after men­stru­ation, or after the birth of a child. Be­fore the be­gin­ning of Shab­bat im­mers­ing often be­longs to the pre­par­a­tions for the weekly day of rest.

Who­ever con­verts to Juda­ism, com­pletes the con­ver­sion by im­mers­ing in the Mik­veh.

Many law-abid­ing Jew­ish men reg­u­larly visit a mik­veh. Nowadays, there is no ex­pli­cit Torah ob­lig­a­tion for a man to im­merse into the water. In the course of time, how­ever, cus­toms have de­veloped, and many men go to the mik­veh be­fore the high hol­i­days. Some visit a mik­veh be­fore every Shab­bat or hol­i­day, Hassi­dim al­most every day.

New crock­ery and kit­chen utensils for or­tho­dox house­holds and kit­chens should also be im­mersed in the Mik­veh to be pure.

The Mik­veh tra­di­tion­ally a room for mar­ried and pro­cre­at­ive women causes dis­cus­sions nowadays. Some in­ter­prete the com­mand­ments for women are seen as a lack of equal­ity or an af­front to­wards women not able get­ting preg­nant or after the meno pause. Some young Jew­ish women and fem­in­ists de­vel­op very per­son­al rituals, even after harsh or trau­mat­ic events in life. In re­cent dec­ades, the mik­veh is seen as a place of fe­male spir­itu­al­ity, too.

In the Talmud (Kid­dush­in 30a) it says that G"d him­self is the mik­veh for the Jew­ish people who pur­i­fies them when their hearts are turned to him.

A mik­veh is a space in which everything is in flux. Where all thoughts can flow and de­vel­op.