We continue our discussion of the construction of mikva’ot by exploring how one directs rainwater into the mikvah in a halachically acceptable manner.
Defining Mayim She’uvim
In the last chapter, we distinguished between the two bodies of water that purify, a ma’ayan (natural spring) and a mikvah (collection of rainwater). The Sifra (commenting on Vayikra 11:36) draws a parallel between them, teaching that just as God creates ma’ayanot naturally, without human intervention, so, too, must the water in a mikvah reach it without passing through receptacles.1Conceptually, passing through man-made receptacles indicates human intervention, as opposed to a natural process directed by God. However, the Sifra does provide one exception. If no human indicated any interest in water passing through the receptacle, then the water remains acceptable for mikvah use. For example, if someone places his pot outside to dry in the sun, and then rain falls unexpectedly, whatever rainwater collects in the pot does not automatically become she’uvim, as the pot’s owner - seeking to dry his pots in the sun - clearly does not desire the water. However, if the owner, upon realizing that his pot contains water, lifts the pot to use its water, then the water becomes she’uvim. Thus, in order to use the water for a mikvah, the owner must knock over the pot without lifting it, allowing the water to continue its natural flow without human redirection. Moreover, had the owner initially placed the pot outside for the purpose of collecting rainwater, then the water would become she’uvim the moment it enters the pot - even if the owner promptly knocks the pot over - because the pot received the water as a result of deliberate human actions (see Mishnah, Mikva’ot 4:1). If, for example, one drew water from a well with a bucket and then poured the water into a pit, the water would be considered mayim she’uvim (drawn water) and would hence be disqualified for use in a mikvah. In the modern context, water from the tap constitutes mayim she’uvim because it passes through receptacles in purification plants and water meters.2Rav Moshe Heinemann explained this fact in a lecture to the Council of Young Israel Rabbis. In previous generations, the Aruch Hashulchan (Yoreh Deah 201:169) and Rav Moshe Feinstein (cited in Taharat Hamayim, Chapters 40-42) actually permitted building mikva’ot with tap water under extremely dire circumstances, but Rav Yirmiyah Katz (Mikveh Mayim, vol. 3 pp. 93-95) argues that water today passes through many places between the reservoir and the faucet that did not exist a couple of generations ago, so nobody would permit using tap water nowadays. Indeed, Rav Moshe himself writes that tap water should generally be presumed to be unacceptable for mikva’ot (Teshuvot Igrot Moshe, Y.D. 3:63).
Since rainwater must reach the mikvah without ever having been in a receptacle, the pipes that bring the water to the mikvah must not include any cavity (beit kibul), which would halachically define the pipe as a receptacle. Thus, the pipes should be smooth, without indentations.3Shulchan Aruch (Yoreh Deah 201:36). Regarding indentations that develop naturally over time, see Rama (ibid.) and Pitchei Teshuvah (Y.D. 201:24). Ideally, elbow pipes should be avoided, as the Ra’avad (gloss to Rambam, Hilchot Mikva’ot 8:7) indicates that they constitute a receptacle.4For a lengthy discussion of the practical aspects regarding pipes that are used to transport rain from the roof to the mikvah, see Mikveh Mayim (vol. 3 pp. 142-218.)
Level of the Prohibition of She’uvim
The Rishonim debate whether mayim she’uvim are5Although the English word “water” is singular, its Hebrew equivalent, “mayim,” is plural. disqualified on a Biblical or rabbinic level. Rabbeinu Tam and the Rashbam (cited in Tosafot, Bava Batra 66a s.v. Michlal) believe that a majority of mayim she’uvim invalidates a mikvah on a Torah level, while the Rabbis enacted that a smaller amount can also disqualify it, as we shall soon see. They note that the aforementioned Sifra derived the concept of mayim she’uvim from a verse in the Torah, so some circumstances must exist where mayim she’uvim invalidate a mikvah on a Biblical level.
On the other hand, the Rambam (Hilchot Mikva’ot 4:1-2) and Ri (cited in Tosafot, ibid.) claim that the entire problem of mayim she’uvim exists only on a rabbinic level, while the Torah itself even permits a mikvah comprised entirely of mayim she’uvim. Although the Sifra derives the concept of she’uvim from a verse in the Torah (Vayikra 11:36), the Rambam believes that the Sifra merely intends that the Rabbis saw an allusion (asmachta) in the Torah to their enactment. The Aruch Hashulchan (Y.D. 201:11-17) reviews two additional opinions that appear in the Rishonim.
The Rama (Y.D. 201:3) disqualifies a mikvah on a Torah level if it contains mostly mayim she’uvim, in accordance with Rabbeinu Tam. Although the Shulchan Aruch does not explicitly address this dispute, the Shach (Y.D. 201:17,117) notes that he repeatedly implies that even a mikvah comprised entirely of mayim she’uvim is invalid only on a rabbinic level.6See, however, Taz (Y.D. 201:63 and 201:84), who apparently believes that the Shulchan Aruch agrees with the Rama.
The Rabbinic Level: Three Logim
Regardless of how one interprets the laws of mayim she’uvim on a Biblical level, everyone agrees that three logim (a Talmudic measure) of mayim she’uvim suffice to disqualify a mikvah on a rabbinic level (Eiduyot 1:3, Mikva’ot 2:4). Rav Heinemann stated that we treat three logim as the equivalent of less than one quart.7Three logim are 1/320 of forty sa’ah. Thus, our contemporary practice is extremely stringent. By assuming that three logim are less than one quart while forty sa’ah are over a thousand quarts, we follow the smallest possible view for the minimum quantity of mayim she’uvim that can invalidate a mikvah, yet we do not use the mikvah until it contains the largest possible interpretation of forty sa’ah. Accordingly, this relatively small amount of water can invalidate the contents of an entire mikvah. However, once the mikvah contains forty sa’ah of acceptable water (over one thousand liters, as we have mentioned in previous chapters), then adding mayim she’uvim to the mikvah does not disqualify it (Mikva’ot 2:3 and 6:8).
Although space does not allow us to discuss them in depth, we should mention that a number of other ways exist to disqualify rainwater for use in a mikvah. These include discoloration (shinui mar’eh), the water entering the mikvah via an item that can become ritually impure (havayato al y’dei tum’ah), and human involvement in the water’s transportation to the mikvah even without using a receptacle (tefisat y’dei adam). These issues all appear in the Shulchan Aruch and its commentaries in Yoreh Deah 201, and Rav Yirmiyah Katz thoroughly discusses their practical ramifications in his three-volume work, Mikveh Mayim.
Making Mayim She’uvim Acceptable – Hamshachah
Pits of rainwater located in caves often served as mikva’ot in Talmudic times. After a short while, however, these mikva’ot became dirty and difficult to use. Consequently, people would bathe to clean themselves after immersing in the mikvah, a practice that the Rabbis disliked.8The Gemara (Shabbat 14a) explains that by bathing immediately after leaving the mikvah, people came to think that the bath water purified them, rather than the mikvah water. Today, in order to prevent such dingy conditions, we fill our mikva’ot with tap water, and regularly drain and refill them. However, as we have already explained, tap water has the status of mayim she’uvim, so we will now examine how contemporary mikva’ot solve this problem.
If three logim of mayim she’uvim reach a mikvah before it has forty sa’ah of rainwater, the mikvah remains disqualified no matter how much rainwater is added. However, the Halachah provides several ways to remedy the water’s status as mayim she’uvim. One such way, the process of hamshachah, consists of pouring the mayim she’uvim on the ground outside the mikvah, leaving them to naturally flow from there into the mikvah.9For a conceptual analysis of the process of hamshachah, see Rav Yitzchak Ze’ev Soloveitchik’s commentary to Temurah 12b. The Gemara (Temurah 12a) records that if the mikvah contains over twenty sa’ah of acceptable rainwater, then Rabbi Eliezer ben Yaakov permits obtaining the rest of the forty sa’ah by running mayim she’uvim along the ground into the mikvah. The Rambam (Hilchot Mikva’ot 4:8) and Shulchan Aruch (Y.D. 201:44) codify his opinion.
The Radbaz (Teshuvot 1:85) prohibits deliberately using hamshachah to bring water into a new mikvah. He asserts that we permit hamshachah only if b’dieved (post facto) water unintentionally reached a mikvah in this manner. Rav Moshe Feinstein (Teshuvot Igrot Moshe, Y.D. 3:64:3) and Rav Yonatan Shteif (Teshuvot 142) rule accordingly.
The Rishonim dispute several details related to the process of hamshachah. For example, the Rambam (Hilchot Mikva’ot 4:9) cites and rejects the view of some anonymous sages who believe that an entire mikvah may be created through the process of hamshachah.10Some attribute this view to the Rif and Rashi (see Beit Yosef, Y.D. 201). On the other hand, the Chazon Ish (Y.D. 130:14) indicates that he believes the Ra’avad disqualifies a mikvah on a Torah level if all of its water entered via hamshachah. Tosafot (Bava Batra 66a s.v. Michlal) suggest a middle position (between the Ra’avad’s view and the view of the anonymous sages cited and rejected by the Rambam), that a mikvah whose water consists entirely of mayim she’uvim revitalized through hamshachah is disqualified only on a rabbinic level. Many (but not all) later authorities adopt this approach.11These authorities include Tashbetz (3:12), Maharit (Teshuvot, Y.D.2:17), Yeshu’ot Ya’akov (201:15), and Chazon Ish (Y.D. 126:1 and 130:14).
Authorities also debate whether water must move across a minimum area of land in order to qualify as hamshachah. The Beit Yosef (Y.D. 201 s.v. Shiur Hamshachah) cites a debate among the Rishonim regarding whether the water must roll along the ground for three tefachim (handbreadths, approximately nine to twelve inches), or perhaps even a tiny bit of land suffices. The Shulchan Aruch (Y.D. 210:45) rules in accordance with the strict opinion that three tefachim are required. Interestingly, the Chazon Ish (Y.D. 126:6) adds that the three tefachim for hamshachah may curve, rather than move in a straight path.
A third debate surrounds what type of ground may be used for hamshachah. The Shulchan Aruch (Y.D. 201:46) rules in accordance with the majority of Rishonim, who permit any surface for hamshachah. The Rama (ibid.), though, comments that it is proper to follow the strict opinion of the Mordechai that the surface used for hamshachah must be capable of absorbing water. Early twentieth-century-authorities debate the permissibility of cement, which includes dirt as a major component. Rav Meir Arik (Teshuvot Imrei Yosher 2:67 and 85) claims that one should not do hamshachah on cement because it does not absorb, while the Chazon Ish (Y.D. 123:1) and Maharshag (Teshuvot 1:65 and 2:6) rule that cement is regarded as absorbent for the purpose of hamshachah.12At first glance, this argument seems quite peculiar, for we should be able to simply pour water on cement and observe whether it absorbs the water. The Chazon Ish, however, explains that cement has the halachic status of earth (presumably because it is the primary ingredient) whose nature is to be absorbent. Accordingly, even though cement does not absorb water, it is defined as a substance that absorbs water since from a halachic perspective it has the status of earth. In addition, see Cheishev Ha’eifod (150:5) for further discussion of this issue. Rav Shlomo Dichovsky (Techumin 16:117) remarks that we rely on the latter view in practice. Rav Yirmiyah Katz (Mikveh Mayim, vol. 3, p. 228) adds that some adopt a compromise view by using cement that contains an unusually high concentration of dirt.
Rav Dichovsky (Techumin 16:117) further notes that most mikva’ot employ the process of hamshachah as an added precaution to insure the mikvah’s validity. Thus, in most contemporary mikva’ot, any water that enters the mikvah moves along the ground on its way. Many poskim recommend this setup because it immediately reduces any concern for mayim she’uvim from a Torah level to merely a rabbinic level.13Teshuvot Igrot Moshe (Y.D. 1:119) and Teshuvot Maharsham (1:145).
Hamshachah alone reduces concern for sheu’vim to the rabbinic level, but it does not completely permit tap water. In order to completely permit tap water, we also employ the methods of hashakah and zeri’ah, which we will now discuss, to permit the actual use of tap water in our mikva’ot even on a rabbinic level.
Hashakah
Hashakah (literally, “kissing”) means that two bodies of water can become one entity by their waters meeting each other. For example, if the waters of a valid mikvah touch the waters of an adjacent pool of tap water, this “kiss” unites them as one body. Since the valid mikvah already contains forty sa’ah of rainwater, the addition of the neighboring mayim she’uvim does not invalidate it. Instead, the pool’s contents now lose their status as mayim she’uvim and obtain the status of the mikvah’s rainwater. One may thus purify oneself by immersing in the pool of tap water, too.
In order to practically implement hashakah, we construct two adjacent pools, separated by a common wall. Pipes that do not create a problem of mayim she’uvim (see our discussion above) direct rainwater into one pool, after which we fill the other with tap water. The tap water “kisses” the rainwater through a hole in the adjoining wall, rendering both pools fit for immersion. When the tap water is changed periodically to ensure a high level of cleanliness, the new water touches the rainwater through the hole, thereby remedying its prior status of mayim she’uvim.
The Mishnah (Mikva’ot 6:7) formulates a general principle that merging two mikva’ot requires a hole the size of a shefoferet hanod (the opening of a container), which it equates with a diameter that comfortably fits two fingers. Conversions of this measurement into inches range from approximately 1.5 inches (Rav Avraham Chaim Na’eh, Shiur Mikvah, p. 163) to three inches (recommended by Teshuvot Igrot Moshe, Y.D. 2:89). According to the Shulchan Aruch (Y.D. 201:53), this measurement is necessary only when one of the bodies being merged is invalid on a Biblical level.14For example, if one of the mikva’ot contains less than forty sa’ah, then it must be connected to a larger mikvah through a hole the size of a shefoferet hanod. A mikvah of mayim she’uvim, though, is invalid only rabbinically,15According to the Shulchan Aruch, as we explained earlier. so it needs a hole only the size of a strand of hair to merge with a completely valid mikvah (see Beit Yosef, Y.D. 201 s.v. Haba Le’areiv).16We have explained the Shulchan Aruch’s view according to the Shach (Y.D. 201:117). The Taz (Y.D. 201:63 and 201:84), however, would apparently disagree with this interpretation, as he implies that he believes the Shulchan Aruch to invalidate a mikvah on a Biblical level if a majority of its waters are mayim she’uvim. The Rama (ibid.), who disqualifies a mikvah of mayim she’uvim on a Biblical level, disagrees regarding the hole, too, and requires a hole the size of a shefoferet hanod between the two pools.
Assuming (like the Rama) that the hole between the two mikva’ot must be at least the size of a shefoferet hanod, the tap water in the mikvah must reach the top of the hole. In order to determine whether the water has reached this height, Rav Katz (Mikveh Mayim, vol. 3 p. 107) encourages constructing the adjoining wall with two colors of tiles. The color of the tiles below the hole should differ from the tiles above it, so one can easily notice if the water has dropped below the required level. Rav Katz describes several scenarios of how well-meaning people can accidentally invalidate a mikvah that lacks a clear system for easily verifying the water level.
After the two pools have merged, an opinion cited by Rabbeinu Yerucham (26:5) requires the hole between them to remain open at the time of immersion. Otherwise, the tap water loses its connection to the rainwater and returns to its former status as mayim she’uvim. The Rosh (Teshuvot 31:2) and Tur (Y.D. 201) explicitly permit closing the hole, arguing that once the two pools have come into contact, the tap water has been permanently “purified” from its status as mayim she’uvim.17For a conceptual analysis of this dispute, see Rav Chaim Soloveitchik’s commentary to Mishnah, Mikva’ot 1:7. The Shulchan Aruch (Y.D. 201:52) rules in accordance with their view. Nevertheless, the Shach (Y.D. 201:112) concludes that it is best to accommodate the opinion cited by Rabbeinu Yerucham, so most mikva’ot today indeed open the hole whenever someone immerses.
Conclusion
Contemporary mikva’ot include tap water, raising the issue of mayim she’uvim. The process of hashakah alone solves this problem, but we also employ hamshachah as an added precaution. Zeriah, a third process to alleviate concern for mayim she’uvim, will be addressed in the next chapter.
Postscript
Rav Yirmiyah Katz graciously permitted us to reprint the illustrations of hashakah and hamshachah from his Mikveh Mayim. We hope the diagrams enhance and clarify our discussions.