Where is the source for the mikva for women in the torah?
The Torah source is in Leviticus, chap. 15, which discusses the laws of a niddah and a zavah. In today’s practice, we do not distinguish between the two, and after a regular period a woman has to count ‘seven days of cleanliness,’ before immersing in the mikva. The words of the verse, “and she shall be purified,” refer to immersion in the mikva, which are waters that serve to purify those who are ritually defiled (tamei).