When a woman immerses in the mikveh, her entire body including all of her hair must be submerged in the water at one time. In general, anything which adheres to the body or hair and prevents contact with the water invalidates the immersion. Such a barrier is called a chatzitzah.
According to Torah law, a barrier (chatzitzah) invalidates a woman's immersion in the mikveh when it meets two conditions:
(1) it covers the majority of her body;
(2) she minds its presence – that is, it is a substance that she considers foreign and plans ultimately to remove.
The rabbis decreed, however, that a substance meeting only one of these conditions (either it covers the majority of her body or she minds its presence) also invalidates the immersion.
Thus, in practice, a barrier of any size is considered a chatzitzah if it is destined to be removed. Even when the woman does not mind the barrier's presence while she is immersing, if she would normally remove it at some other time (e.g., a ring that she removes only when kneading dough) it is a chatzitzah. Furthermore, if most women would be particular about an item, then it is considered a chatzitzah even for an individual who does not mind its presence.
Every attempt should therefore be made to remove even minute amounts of foreign material before immersing. If, however, a barrier is inconvenient, difficult or impossible to remove, then a rabbi should be asked whether the item is actually a chatzitzah. Some examples are:
1. The foreign material has a medical role (e. g., stitches).
2. Its removal would be dangerous.
3. It serves a cosmetic purpose (e. g., hair color).
4. It is permanently attached to her body.
In such situations consultation is essential. A woman should never assume on her own that foreign material is inconsequential, and risk an invalid immersion, but neither should she take it for granted that it is indeed a chatzitzah, and perhaps needlessly delay immersing in the mikveh.
According to Torah law, any item which covers the majority of the body (rov), and whose presence bothers the person (makpid) is considered a barrier to mikveh immersion (chatzitzah).
According to binding rabbinic decree, an item is also a chatzitzah if it meets only one of the criteria – either rov or makpid. Thus, an item that covers a small portion of the body but is undesired, or that covers the majority even if desired, is a chatzitzah. When calculating the majority, the hair is considered a separate unit. Thus, an item that covers most of the hair is a chatzitzah, even if the rest of the body is not involved.
It would appear that hair dye, which covers a majority of the hair, could present a problem of chatzitzah. In practice, there are several reasons for leniency:
- If a woman clearly wishes an item to be present for cosmetic reasons, then in some cases it may not be considered a chatzitzah.
- Items permanently attached to the body are considered subordinate to the body, and thus are no longer chatzitzot. Therefore, permanent dyes, which stay in the hair through multiple washings, are less problematic than temporary dyes.
- There is room for leniency if an item has no independent substance (it is absorbed into the skin or hair and cannot be felt above its surface). Thus, while efforts should be made to remove unwanted ink and dye stains prior to immersion, if they cannot be removed they are not chatzitzot.
A woman wants the dye for cosmetic reasons, it is permanently absorbed into her hair, and it has no independent substance. Therefore, it is permissible to immerse in the mikveh with dyed hair.
Timing of the hair treatment does raise some practical issues. Women want the dye to be present on the hair, but not on the scalp. Therefore, dye which remains on the scalp immediately after treatment could be a chatzitzah. Dyeing appointments should therefore be scheduled long enough before mikveh for the extra dye to be removed.
On the other hand, the woman's preference for dyed hair is an essential factor in determining that the dye is not a chatzitzah. Therefore, the dye must be well enough maintained for her to feel comfortable being seen in this condition. If the roots have grown out to the point that she would not want to be seen this way in public, the dye is considered chatzitzah. Therefore, if she is planning to stop dyeing her hair, she should use temporary dyes until her hair has grown out to the point that it can be cut and left in a manner with which she is comfortable.
In general, a cast is considered a barrier to immersion (chatzitzah). This is due to the fact that it encloses a part of the body and does not allow the mikveh waters reach the covered section. This is especially true for plaster casts, where the woman also does not want to wet the cast and is diligent to keep it dry.
There are times, however, when immersion with a cast can be permitted if the cast will be on for a long time. Each situation requires individual adjudication to determine the correct course of action. The rabbi will need to know the following information from the doctor:
- How long does the cast need to be in place?
- Is it possible to remove and replace the cast (as is occasionally done for clinical reasons)? What would be the cost of such a procedure?
- Can the cast be left under water for long enough to allow water to seep through without ruining the cast (as may be true for some fiberglass casts)?
The rabbi will also want to know from the woman for how long she will be niddah if she cannot immerse with the cast and whether there any factors that make it particularly hard for her to be niddah for a prolonged period.
Mikveh immersion requires that the entire body be immersed in the water of the mikveh at one time. Under normal circumstances, all foreign objects also need to be removed before immersion so that the mikveh water can reach all parts of the body unimpeded.
However, there are situations where it would be dangerous, painful, or medically problematic for a woman's ears to be exposed to water. In such situations, a specific halachic question needs to be asked, and the woman should work together with her physician and a halachic authority to find a solution that will allow her to use the mikveh. Below are some general principles and guidelines:
(1) The usual practice among Ashkenazi women is to immerse in the mikveh, recite the bracha, and immerse again. Many women also have the custom to immerse additional times. However, in cases where immersion is medically problematic, one momentary immersion is sufficient. The bracha should be recited before the immersion.
(2) The ear canal is considered beit hastarim, a "hidden area" similar to the inside of the mouth. While the mikveh water does not need to actually enter areas defined as beit hastarim, rabbinic law requires that they be free of chatzitzot. However, there is room for leniency in cases of need. Therefore, if water cannot be allowed to enter the ear for medical reasons, a piece of cotton coated in fish oil or vaseline may be placed deeply in the ear prior to immersion. In cases where an ENT has ruled out this option even for one momentary immersion, well-fitted earplugs inserted deep inside the ear might be permitted.