A foreign object that adheres to the body or hair, preventing contact with the water of the mikveh, is called a chatzitzah (barrier), and may invalidate the immersion. Halacha requires that foreign material be removed, even if it does not disturb her or adhere tightly to her body or hair. Knotted hair also constitutes a chatzitzah, as the knots cannot come into full contact with the mikveh water.
To prevent such problems, a woman should follow a series of steps, summarized below, in preparation for immersing in the mikveh. These include both cleansing (chafifah) and inspection (iyun). Most mikvaot have checklists in the preparation rooms to prevent inadvertent omission of any of the required steps.
Chafifah (Cleansing)
Cleansing is required by rabbinic decree. Originally, only a thorough washing of the hair (the literal meaning of chafifah) was required, but the law was subsequently extended to include the entire body. A woman should do the following:
1) She should remove obvious barriers, such as clothing, jewelry, or contact lenses.
2) Bandages should also be removed. If bandages or other items cannot be removed for medical reasons, she should consult a halachic authority.
3) Because dirt beneath the nails is a chatzitzah, the custom is to cut nails short.
4) She should remove all makeup. Long-term cosmetics without independent substance, such as hair dye or permanent makeup, are not considered a chatzitzah. If she has a well-maintained manicure that she is reluctant to remove, she should consult a halachic authority.
5) She should wash her hair with warm water and shampoo. The hair on her head must be thoroughly combed with a comb; other body hair may be separated with the fingers.
6) Hair that is still attached to her body, even where it is undesired (e.g., leg or underarm hair) is not a chatzitzah. But since some authorities maintain that this leniency does not apply to hair about to be removed, a woman who is about to cut or shave her hair should do so before immersing. She should take care to wash away the removed hairs. For this reason it is recommended to shave earlier that day or on the day prior to immersion.
7) She should wash her entire body with soap and water. Preferably, she should use only warm water, but if there is a limited supply, she may wash her body with cold water and save the warm water for washing her hair. While it is customary to bathe in a bathtub, she may take a shower instead, as long as she is careful to wash her entire body.
8) Parts of the body whose natural form prevents water from entering (e.g., the armpits, under the breasts, and other crevices) are known as beit hastarim – hidden places. These areas need not actually come in contact with the mikveh water, but they must not be prevented from doing so by any chatzitzah. Therefore, they must be cleaned thoroughly, and often require special attention. Similar rules apply to internal parts of the body – in particular, the inside of the mouth. Therefore, she should thoroughly brush and floss her teeth. Permanent fillings and crowns are not considered chatzitzot, but temporary dental work may be problematic, and a halachic authority should be consulted.
Iyun (Inspection)
Inspection prior to immersion is required by Torah law.
1) She should visually inspect all visible parts of her body to ensure that they are free of foreign material.
2) She should inspect the other parts of her body by touch.
3) She should check her hair for knots.
