During her menstrual period and after giving birth, the “unclean” woman may not sleep with her husband and may not even touch him. When her flow has ceased, after seven days, she must purify herself in “living waters”; until then she remains Niddah, separated, removed.

A bride must go to the Mikvah before her wedding to be cleansed from the Niddah status that has existed ever since her first menstruation. Newlyweds must separate after the initial consummation of the marriage, on the chance that her discharge may contain menstrual blood.

The Rabbis greatly extended the laws of Niddah. Where Torah states that a woman remains in this state for seven days, the Rabbis ordained that she remains unclean in fact for seven days after the flow has ceased. During this period, which lasts a minimum of twelve days every month, she may not sleep in the same bed with her husband. At nightfall, after the days of menstruation and the seven days of additional impurity have passed, she goes to the Mikvah.

A Mikvah is a special pool, filled with “living waters” as prescribed. The water must be in contact with the ground water of a stream or rainwater caught in a cistern. A Mikvah should not be constructed without rabbinical guidance.

The woman may immerse herself in a stream or in the ocean.

Before entering the Mikvah, the woman takes a bath, cleansing her body thoroughly. She cleans her nails, removes all rings, bandages, anything that can be regarded as a separation between her body and the water. She brushes her hair. Then she steps into the Mikvah, nude. Spreading her arms and legs, she immerses herself fully. Even the last strand of her hair has to be under water.

Tradition has regarded the laws of Niddah as the cornerstone of Taharat ha-Mishpahah, the purity of the family.

The woman was spared the burden of serving her husband at a time of her discomfort.

Forbidden to touch her or to have sex with her for long periods, a husband would not tire of his wife, nor she of him.

The Jewish woman was legally dependent on her husband; yet she was independent. Without the laws of Niddah, she might not have had this dignity and independence. Her husband had to learn through longing. He could not subject her to his whim. This awareness carried over into the total relationship of the partners. Thus he came to honor her, and she to appreciate him.

The wife returns to the marriage bed at the moment of her greatest physiological readiness to conceive; the end of procreation was thus served by the laws of niddah.

During the Middle Ages, Jews were often spared the ravages of epidemics that bred in dirt and came to afflict the general population,. As Jewish women had to cleanse themselves and Jewish men were advised to do so under the rules of purity, Jewish law placed a protective shield about the physical health of the Jew.

Reform Judaism does not feel bound by these laws. Among conservative Jews, practice varies widely.