LEV849 The Torah includes rules that forbid conjugal relations during a woman's menstrual period (Leviticus 15:19-24, 18:19, 20:18). The Torah gives no rationale for these rules apart from saying that they are part of the way in which the people Israel become holy--that is, separated from other peoples and in league with God. While the Torah requires sexual abstinence for seven days, the Rabbis added another five, and so couples who follow these laws do not have conjugal relations for twelve days out of every menstrual month. The woman must immerse herself naked in undrawn waters, which in practice has meant either in a natural body of water or, more commonly, in a mikveh--that is, a pool specially constructed to fulfill the legal requirements.