mikvah, (“collection [of water]”), in Judaism, a pool of natural water in which one bathes for the restoration of ritual purity. The Mishna (Jewish code of law) describes in elaborate detail the requirements for ritually proper water and for the quantity of water required for ritual cleansing. In former times, a mikvah was so essential to each community of Jews that, if necessary, a synagogue could be sold to finance its construction.
With the destruction of the Second Temple of Jerusalem in ad 70, many laws of ritual purity lost their relevance. Consequently, ritual bathing in modern times is much restricted. Traditionally observant Jews, however, still use the mikvah, and converts are required by Halakha (legal tradition) to undergo a ritual bath. Males bathe each Friday and before major festivals, while women use the mikvah (as the law prescribes) before their wedding, after childbirth, and following menstruation.