Immersing in a Mikvah While It Is Still Being Filled

Question:

I came to the local men’s mikvah on Erev Yom Tov, and I noticed that they were in the middle of filling the mikvah with water from the top of the Mikveh. It would have taken at least forty‑five minutes for the mikvah to become completely full. I did not want to wait and immersed anyway, since there was already enough water present for my entire body to be submerged at once. However, afterward I wondered whether the immersion might be invalid because of zochlin—flowing water—which is known to invalidate a mikvah when water is streaming into or out of it. Is immersion under these circumstances indeed invalid? Please clarify.

Answer

With respect to a woman’s immersion, one must indeed be stringent and ensure that no water is flowing into the mikvah while it is open for immersion, due to the concern of zochlin. Consequently, the accepted practice is that the water supply be completely shut off before immersion takes place.

However, with regard to a men’s mikvah, although it is certainly preferable for the water to be turned off before immersion, there is no requirement to be stringent to the extent of waiting an additional forty‑five minutes until the mikvah is entirely full. One may immerse even while the filling process is ongoing.

Explanation

One of the classic invalidations of a mikvah is zochlin—flowing water. This refers to a situation where water is moving continuously, such as when it is flowing out of the mikvah through a crack or opening, which undeniably invalidates the mikvah. The poskim discuss whether this invalidation applies only when water is flowing out, or whether water flowing into the mikvah also constitutes zochlin. Practically, the common understanding for generations was that zochlin applies only when water flows out of the mikvah. However, the Divrei Chaim advanced a novel position, asserting that even water flowing into the mikvah may be considered zochlin and invalidate the immersion. Several later authorities adopt this understanding of his view. On the other hand, many poskim disagree and reject applying zochlin to water that is merely entering the mikvah, limiting the invalidation strictly to cases where water is flowing out.

Practically for a woman’s immersion, the accepted and longstanding custom is to be stringent and ensure that all water flow is stopped, in accordance with the more cautious views. For a men’s mikvah, which is used primarily for tosefet taharah (additional spiritual purity) and to avoid tum’ah of Baal Keri, there is considerable room for leniency, and one may immerse even while the mikvah is still being filled.

An additional factor supporting leniency by a man is that the person immerses below the point where the water is entering the mikvah. According to many poskim, even by a true zochlin the invalidation applies only from the level of the flow and above, whereas the water below that point remains valid. Although this distinction is generally not relied upon for a woman’s immersion, with respect to a men’s mikvah it serves as a further supporting reason to be lenient.

A further factor for leniency with respect to a men’s mikvah is that, according to some poskim, the prohibition of zochlin does not invalidate a man’s immersion at all when the immersion is undertaken for purposes of additional spiritual purity (tosefet taharah) or to remove keri (Ba’al Keri). According to these authorities, the laws of zochlin—even if present—were never applied to such immersions, as they lack the full halachic stringencies required for a woman’s immersion.

Summary: Grounds for Leniency

In summary, there are three independent reasons supporting the permissibility of a man immersing in a mikvah while it is still being filled:

1. According to many poskim, water entering a mikvah is not considered zochlin at all, and therefore does not invalidate the immersion.
2. According to many poskim, even if water entering the mikvah is considered zochlin, the invalidation applies only at and above the point where the water enters, whereas immersion below that point remains valid.
3. According to some poskim, there is no invalidation of zochlin whatsoever with respect to a man’s immersion, since such immersion is performed for supplementary purity rather than for the full halachic requirements applicable to a woman’s mikvah.

Taken together, these considerations establish a strong basis for leniency in the case of a men’s mikvah, even though it remains preferable, when feasible, for the filling to be completed before immersion.

Sources:

See regarding if Zochlin invalidates a mens Mikveh: Yes: Mechzeh Avraham 13 based on M”A 159:27 and Admur 159:22 as explained in Machatzis Hashekel 159 regarding Tevilas Yadayim for bread; Zichron Yehuda 2:62; Vayaan Yosef 46; Beir Moshe 5:21; Minchas Yitzchak 3:64; Piskeiy Teshuvos 88:6; Sheyikadesh Atzmo 63:12. No: Arugos Bosem brought in Teshuvah of Zichron Yehuda, brought in Minchas Yitzchak 3:64

See regarding if water entering a Mikveh is defined as Zochlin: See Mikveh Mayim Chapter 10 p. 136; Encyclopedia Talmudit Erech Zochlin Vol. 12 footnotes 48-49 Yes: Divrei Chaim Mikvaos based on Rivash 292 and Shach 201:30; Darkei Teshuvah 201:13; Shoel Umeishib Mahadurah Daled 3:47; Chidushei Harazah 18; Chazon Nachum 69; Chibur Letaharah 2:42; Doveiv Meisharim 1:69; Divrei Yechezkal Shraga 14; Hagaon Mikomrana in his Pirush on mishnayos Mikvaos 4; Divrei Yatziv Y.D. 114; Divrei Moshw 65; No: Mei Hashiloach 2:7-8 based on Shach 201:12 and 33; Divrei Yoel Y.D. 71; Yagel Yaakov Y.D. 82; Vayechi Yosef p. 97

See regarding if water below the flow is also defined as Zochlin: See Michaber and Rama 201:50; Mikveh Mayim 2 p. 1-13; Encyclopedia Talmudit Erech Zochlin Vol. 12 footnotes 22-49  Yes: Rama ibid; Mordechai Shavuos 745, Rashba Shaar Hamaim 2; Tur 201; 1^st Pirush in Rash; Gidulei Taharah; Tzemach Tzedek 176; Emek Sheilah 55; No: Michaber ibid; Rosh Mikvaos and Teshuvos 31:4; Eshkol 60; Tashbeitz 1:17; 2^nd Pirush in Rash; Maharik 156; Tzemach Tzedek 165