Leviticus 18:19 contains the laws referred to as taharat hamishpachah (literally, ‘family purity’). According to these and other Jewish laws relating to ritual impurity, a man is forbidden to approach a woman during the period of her menstruation and for seven days after in order to have sexual relations with her. This practice originated in Biblical times, although the laws relating to it have developed over the course of Jewish history.
The traditional implication of ritual impurity was that the person who was in this state could not enter the Temple. It was believed that the state of ritual impurity could be passed on in different degrees in a variety of ways, including sexual intercourse, touching, spitting, and even sitting on the same bed or stool.
Since the destruction of the Temple, the Jewish laws of ritual purity have been widely misinterpreted. The notion that women are impure because they menstruate is mistaken, because Judaism holds that all Jews today are in the state of ritual impurity, not only menstruating women. This is because Jews no longer have a red heifer, whose ashes were used to take us out of the state of ritual impurity. Today all of us, men and women, are ritually impure.
In Leviticus 15, the laws of genital discharges which are tameh (ritually impure) are laid out. According to these laws, a Jewish man with a regular seminal discharge, a shikhvat zerah, is considered ritually impure until the following evening. A menstruating woman, a niddah, is ritually impure for seven days from the start of her flow. A man who has a sickly penile discharge (zav) is tameh for the duration of the discharge and for seven days after; likewise a woman who has an irregular flow of uterine blood (zavah).
The practice of taharat hamishpachah, as it is known in contemporary Judaism, is not identical to the Biblical laws of niddah. The laws we have today are actually a combination of the laws of niddah and zavah. The history of the conflation of niddah and zavah dates back to Talmudic times and it is unclear as to exactly why such stringency was adopted. It may be because of the difficulty of keeping track of what was niddah and what was zavah.
In the book of Exodus (19:25) Moses tells the Israelite men to separate from their wives three days before the receiving of the Torah. Thus rabbinical law concludes that a woman must wait until 72 hours have passed after her menstrual period ends, before she is considered pure for the purposes of sexual intercourse. An additional day was added because 72 hours can span four calendar days, and a fifth in case the couple had intercourse during twilight (a time that is considered both day and night according to Jewish law).
Once the woman has counted her seven clean days, she washes herself thoroughly, removes any jewelry, makeup, contact lenses and stray hairs, and immerses herself in the mikvah (ritual bath). The water of the mikvah must touch every part of her body. This is why before entering it she must remove anything that could act as a barrier; she goes into the mikvah absolutely clean and naked.
Immersion is the ritual that changes the status of the woman, much the way that immersion in the mikvah changes the status of a non-Jew to a Jew in the case of conversion. When the woman emerges from the mikvah, she is no longer in a state of niddah. Therefore she can have intercourse with her partner, even though both she and he are still considered to be ritually impure according to the ancient laws.
There is also a set of laws relating to niddah, those governing the relations and interactions (other than intercourse itself) between a man and woman during the period of niddah. As a preventative measure to ensure that a couple would not engage in sexual intercourse during this minimum twelve-day period, the rabbis instituted prohibitions against any kind of sexual intimacy during this time. The origins of these laws date back to the Talmud, although they increased in stringency over time.
What is clearly forbidden in the Talmud, BT Ketubot 61a, is for the woman to pour wine for the man, wash his hands and feet, and make up his bed. However, even there the Talmud allows for the first to be done if she passes the wine glass in a way that is different from the way she usually does. There is a discussion in BT Shabbat 13a about whether or not the couple can sleep in the same bed together during the niddah period if they are both wearing clothing. What is clear from that discussion is that sleeping nude in the same bed is forbidden. There is even the suggestion that any touching at all during the niddah period is forbidden. The Shulchan Aruch (Code of Jewish Law), Yoreh Deah, Hilchot Niddah, Section 195, goes further than this, forbidding a whole series of activities not mentioned in the Talmud, including the passing of objects between the couple.
The laws of family purity are complicated and extremely personal in nature. It is therefore advisable that any couple considering following them find a knowledgeable and sensitive teacher who can both teach them the laws and counsel them on the best way for them, personally, to integrate them into their marital life.
If questions arise, a knowledgeable authority should be consulted, since unnecessary strictures can lead to unnecessary sexual abstinence, which in itself is not a virtue within the context of Jewish marriage and can also lead to the prevention of the performance of the commandment to “increase and multiply”.