The Building and Maintenance of Mikva’ot - Part Five by Rabbi Chaim Jachter


Five Approaches to Creating a Mikvah

We have outlined, in the previous two issues, the procedure for creating Mikva’ot.  People immerse in a pool of tap water that is fundamentally unsuitable for immersion.  We render the tap water suitable for immersion through the process of either Hashakah or Ze’riah.  Hashakah involves the tap water in the immersion pool touching the rainwater in an adjacent pool (Bor Hashakah) and Ze’riah involves running tap water through a pool containing rainwater, which subsequently enters the immersion pool.  This week we will outline five approaches to creating a Kosher Mikvah.

The Jerusalem and Rav Moshe Feinstein Approach– Hashakah and Ze’riah

Last week we discussed that the traditional practice in Jerusalem and the approach advocated by Rav Moshe Feinstein is to employ both the process of Hashakah and Ze’riah.  We employ Ze’riah in addition to Hashakah as a back up in case of failure in the execution of the Hashakah process.  Ze’riah alone does not suffice because it appears to fail to satisfy the opinion of the Ra’avad that more than twenty Sa’ah (five hundred liters) of the original rainwater must remain in the pool to be suitable to Kasher Mayim She’uvim (“drawn water” that is unacceptable for immersion, such as water from the tap).  We refer this issue as the opinion of the Ra’avad concerning Natan Sa’ah V’Natal Sa’ah.  The Jerusalem tradition and Rav Moshe believe that the use of a Bor Hashakah satisfies this opinion of the Ra’avad, because the water in the Bor Hashakah is more stable than that of the Bor Ze’riah.

The Hungarian and B’nei Brak Approach – Ze’riah Alone

Last week we also discussed that the approach in prewar Hungary (following the Chatam Sofer) and Bnei Brak (following the Chazon Ish) is to use the Ze’riah approach and not the Hashakah approach in creating Mikva’ot.  The advocates of this approach believe that Hashakah is unnecessary, as it cannot accomplish more than Ze’riah.  They believe that the process of Hashakah does not satisfy the opinion of the Ra’avad concerning Natan Sa’ah and Natal Sa’ah any more than the process of Ze’riah.  They believe that the original rainwater in the Bor Hashakah will in short order be removed in the exchange of water that occurs between the immersion pool and the Bor Hashakah.  They are not particularly concerned that their approach does not satisfy the opinion of the Ra’avad as most Rishonim reject this opinion and the Shulchan Aruch and most of its commentaries rule against the Ra’avad.  Even Rav Mose Feinstein (Teshuvot Igrot Moshe Yoreh De’ah 1:111) notes that the Ra’avad’s view constitutes a Da’at Yachid (a singular opinion) that we strive to satisfy, but it is not fatal to the Kashrut of a Mikvah if we fail to do so. 

The Divrei Chaim Approach – Ze’riah and Momentary Hashakah

Some Mikva’ot employ an approach that is based on a responsum of Rav Chaim of Sanz (Teshuvot Divrei Chaim Choshen Mishpat 37).  This approaches seeks to satisfy all opinions by employing both Ze’riah and a momentary Hashakah.  A momentary Hashakah involves the opening between the Bor Hashakah and immersion pool being closed save for a brief moment when it is opened to allow the waters to touch.  In this manner, the original rainwater in the Bor Hashakah is preserved.  It is primarily, as noted by the Chazon Ish, during the time when people immerse that water is exchanged between the two pools as immersions cause the water to rise.  Thus, there is hardly any opportunity for the original rainwater in the Bor Hashakh to be lost if the opening is closed during immersion.

A problem with this approach is that the Shach rules (as we discussed in a previous issue) that it is best that the opening between the pools be open during the time of immersion in order to satisfy the opinion cited by Rabbeinu Yerucham that a momentary Hashakah is inadequate.  A response to this argument is that the Shulchan Aruch and most of its commentaries rule in accordance with the opinion of the Rosh that even a momentary Hashakah suffices.  Moreover, we satisfy the opinion cited by the Rabbeinu Yerucham by using the Ze’riah process.  Ze’riah is performed to satisfy those who believe that momentary Hashakah is inadequate.

Most Mikva’ot do not employ the Divrei Chaim approach because they believe that the opinion of the Ra’avad is the conceptual equivalent of that of Rabbeinu Yerucham.  Rabeinu Yerucham (as explained by many Acharonim, including Rav Chaim Soloveitchik) believes that the tap water remains fundamentally inadequate for immersion unless it is actively connected with a Kosher rainwater pool.  Those who disagree believe that the tap water is fundamentally transformed from disqualified water to Kosher water at the moment of contact with the Kosher rainwater pool.  Thus, it need not maintain its connection to the Kosher rainwater pool.  Similarly, those who reject the Ra’avad believe that a majority of the original rainwater need not be present in the Bor Ze’riah since the tap water that enters the Bor Hashakah is transformed into Kosher water.  The Ra’avad is strict because he believes that the disqualified water fundamentally remains not Kosher, and is Kashered only because of its contact with the original rainwater.  Thus, the Divrei Chaim method might not satisfy the Ra’avad because the Ra’avad seems to agree with Rabbeinu Yerucham that a momentary Hashakah is inadequate.  The issue of whether the Ra’avad’s view is conceptually identical with the Rabbeinu Yerucham is vigorously debated among the Acharonim.  Teshuvot Tzemach Tzedek Y.D. 171, Teshuvot Amek She’eilah Y.D. 48, and Gidulei Taharah (responsum number 10) argue that the two opinions are identical and Teshuvot Beit Shlomo (2:Y.D. 68), Teshuvot Maharshag (1:65), Teshuvot Divrei Yoel (Y.D. 71), and Teshuvot Igrot Moshe Y.D. 3:63) argue that the two opinions are not identical.  For a summary of this debate see Rav Yirmiyah Katz’ Mikvah Mayim 1:47-52). 

The Lubavitch Mikvah – “Bor Al Gabei Bor” Style of Hashakah

Rav Shalom Baer Schneersohn, who served as the Lubavitcher Rebbe from 1866-1920 (known to Chassidim as “The Rebbe Rashab”) innovated a new style of creating Mikva’ot.  This has become the standard manner of creating Mikva’ot for Lubavitch Chassidim and is commonly referred to as the “Lubavitcher Mikvah”.  This innovation generated an incredibly vigorous debate that is summarized by Rav Katz in his Mikvah Mayim (1:53-88).  Rav Shalom Ber’s instructions for creating a Mikveh were recorded by his student Rav Yaakov Landa (who served for many years as the Rav of Bnei Brak) and appear in Rav Nissin Telushkin’s Taharat Mayim.

Traditionally the hole that connects the immersion pool with the Bor Hashakah is on the sidewall of the Mikvah.  Rav Shalom Ber introduced the concept of placing the Bor Hashakah on the bottom of the immersion pool and the hole between the Mikva’ot on the bottom of the immersion pool.  Rav Shalom Ber also added that two holes should be made at the bottom of the Mikvah, to insure constant contact between the two pools in case someone steps on one of the holes.  He also added that the holes should be the size of a Tefach (handbreadth, four inches) by a Tefach instead of a Sh’foferet Hanod (the opening of a container, one and a half inches to three inches) as in taught in the Mishna.  The reason for this requirement remains a mystery although many have attempted to offer explanations (Teshuvot Minchat Yitzchak 5:23, Teshuvot Shevet Halevi 2:104, and Mikvah Mayim 1:65-66). 

These innovations attain at least three very significant achievements.  First, it eliminates concern lest the caretaker of the Mikvah forget to open the hole between the immersion pool and the water storage pool, because the hole is always open.  Second, it eliminates concern that the water in the immersion pool should be filled to the height of the hole in the sidewall of the Mikvah. Third, it seems to satisfy the Ra’avad’s requirement that the original rainwater remain in the Bor Hashakah.  This is because the water in the immersion pool is heated and the water in the Bor Hashakah is not heated (because no one immerses there).  Hot water rises, cold water falls, and thus there is little concern that the rainwater in the Bor Hashakah will be lost.  Moreover, the expense for creating a Mikvah is greatly reduced as there is no need for more than two pools of water and there is less need for land as the Bor Hashakah is built on the bottom of the immersion pool.  This makes this type of Mikvah ideal for Lubavitchers who engage in outreach in remote corners of the globe and need an easier way to build and manage a Mikvah. 

Although this approach appears to be ideal, it has met considerable opposition.  The Teshuvot Divrei Chaim (2:88), in a celebrated responsum, criticizes this approach.  He cites the Mishna (Taharot 8:9) that states “Katafres Ei’no Chibbur”, water that is flowing along a slope into a Mikvah is not considered to be attached to the Mikvah.  The Divrei Chaim argues that this rule teaches that waters are considered to be Halachically combined only if they lay side-by-side but not one above the other. 

                Many Poskim defended the Mikvah of Rav Shalom Ber from the criticism of the Divrei Chaim.  The Gulot Aliyot (a major work on the Halachot of Mikvah), section four, argues that the rule of Katafress Eino Chibbur applies only when the water is flowing on a slope and not when the two pools are stationary.  Rav Shlomo Ganzfried (the author of the Kitzur Shulchan Aruch who wrote an authoritative work on Hilchot Mikva’ot entitled Lechem V’Simlah) argues (Simlah 98) that Katafress Eino Chibbur does not apply when the two pools that are located one above the other are connected deliberately.  The Pnei Yehishua (in his commentary to Gittin 16a) argues that Katafress Eino Chibbur does not apply when the water that connects the two Mikva’ot are from the Mikva’ot themselves (as opposed to an external source).  Teshuvot Chatam Sofer (Y.D.96) argues that this rule does not apply if there is abundant water that connects the two Mikva’ot.

Moreover, it seems that even the Divrei Chaim would accept the Lubavitch Mikvah as they are commonly constructed.  First, the Divrei Chaim writes (in his introduction to Hilchot Mikva’ot number five) that we do not say Katafress Eino Chibbur when the water has had its status as Mayim She’uvim mitigated to a rabbinic level disqualification by the process of Hamshachah (a process that we described at length in an earlier issue).  In fact, the Rash in his commentary to the Mishna (Mikva’ot 6:8) states that we do not say Katafress Eino Chibbur if the water is disqualified only on a rabbinic level.  Recall that the Hamshachah process is a standard feature of most Mikva’ot today.

Furthermore, when the two Mikva’ot lie directly upon each other with only the separation of a floor, even the Divrei Chaim seems to agree that the Mikvah is Kosher.  This is because in this situation we do not have two Mikva’ot that need to be connected.  Rather, we regard the two pools conceptually as one large pool.  Indeed, four major authorities on Hilchot Mikva’ot accept this type of Mikvah without qualification – Rav Meir Arik (Teshuvot Imrei Yosher 2:73), Rav Moshe Feinstein (Teshuvot Igrot Moshe Y.D. 3:65) the Satmar Rav (Teshuvot Divrei Yoel Y.D. 80), and Dayan Weisz (Teshuvot Minchat Yitzchak 2:92).  In practice, Lubavitch Mikva’ot are created in this manner.  In fact, in many communities the Mikvah built for Tevilat Keilim is built on this principle even if the regular Mikvah in that community is not.  A motivation for this is usually economic, as there is not as great a need to be strict regarding a Mikvah for Tevilat Keilim as there is for a regular Mikvah.

Rav Yaakov Breisch – The Split Level Bor Hashakah

Rav Yaakov Breisch (when he built a Mikvah in Zurich in 1959) introduced a manner of creating a Mikvah that attempts to satisfy the Ra’avad’s requirement that more than twenty Sa’ah of the original rainwater be preserved in the Mikvah.  His Mikvah (as he describes in his Teshuvot Chelkat Yaakov 3:53) contains both a Bor Ze’riah and a Bor Hashakah.  However, he had a very large Bor Hashakah (that contains more than twice the required amount of rainwater) filled with rainwater.  He subsequently placed a fiberglass sheet with a tiny hole in the middle of the Bor Hashakah to create two Mikva’ot.  The upper Bor Hashakah is connected to the immersion pool while the bottom Mikvah of the Bor Hashakah is not.  Thus, even if one accepts the Chazon Ish’s contention that the Bor Hashakah loses its original rainwater, the bottom Mikvah in the Bor Hashakah shouldl retain the original rainwater.

 In effect, Rav Breisch improves upon the Lubavitch Mikvah, in that his Mikvah also has a Hashakah from side to side and since no one enters the top Mikvah in the Bor Hashakah chances are even greater that the rainwater in the bottom Mikvah will be preserved.  Moreover, the two Mikva’ot in the Bor Hashakah are connected by only a tiny opening, which even further reduces the opportunity for the original rainwater to be lost.  The reason why a tiny hole is sufficient is that the hole is not Kashering disqualified water, rather it is maintaining a connection between two bodies of waters that were once connected and started as Kosher.  The Rosh (commentary to Mikva’ot 6:8) states that the need for a hole the size of a Sh’foferet Hanod applies only when the Kosher water in one Mikvah is needed to Kasher disqualified water in a second Mikvah.

Rav Breisch’s innovation has been well received, generally speaking.  Many Mikva’ot throughout the world are built on this system (with some minor variations in some places).  Dayan Weisz (Rav Breisch’s “Mechutan”) accepted this approach and implemented it in the Mikvah he built in Manchester in 1957 (Teshuvot Minchat Yitzchak 2:23).  Rav Moshe Feinstein (Teshuvot Igrot Moshe Y.D. 3:65), though, argued that although this Mikvah is Kasher, it does not satisfy the opinion of the Ra’avad any more so than a traditional Bor Hashakah.  Rav Moshe argues that the Gemara’s principle of Yeish Bilah (Zevachim 80), that waters that touch are considered to mix completely, runs counter to Rav Breisch’s assertion that the water in the bottom Mikvah does not mix with the top Mikvah.  Rav Moshe even believes that the principle of Yeish Bilah overrides empirical evidence (from a test conducted with dye) that water from the bottom Mikvah does not mix with the top Mikvah.  Rav Nissin Telushkin (Taharat Mayim p.270) and Rav Yirmiyah Katz (Mikvah Mayim 67-70 and 99-106), on the other hand, criticize Rav Moshe’s application of this principle to Rav Breisch’s Mikvah.  For further discussion of this Mikvah also see Rav Moshe Shternbuch’s Mo’adim U’Zmanim (4:310) and Mikvah Mayim (1:107-124).


It is important to note that each of the five styles of Mikva’ot that we have described are Kosher beyond a doubt.  Indeed, Rav Moshe Feinstein (Teshuvot Igrot Moshe Y.D. 1:111 and 3:65) states that all five variations of creating a Mikvah are undoubtedly Kosher.  The only question is whether certain stringencies are satisfied in a more effective manner in one style more so than another.  We hope that this five part series on Mikva’ot has been enlightening for our readers.  We hope that it has opened our readers’ eyes to the profoundly rich literature pertaining to the Halachot of Mikva’ot.  Indeed, the great Halachic authorities of all generations have expended great energy discussing and probing the Halachot of Mikva’ot to insure that our Mikva’ot be created and maintained at the highest possible Halachic standards.

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