THE MAKING OF A MIKVAH
Bava Basra 66a discusses the invalidation of מים שאובים, drawn water, and is a parallel passage to Bava Kama 67a where Daf Topics discussed historic mikvaos and demonstrated that almost all ancient mikvaos were based on מעינות, springs or groundwater supply. Moving forward in time, we shall discuss the different challenges encountered, so that we can understand the various arrangements found in modern mikvaos. Let us make a preliminary remark about the Rabbinical practice to act exceptionally strictly regarding mikvah construction and maintenance. From earliest times Rabbonim seek to accommodate even minority opinions which would usually be disregarded. Rabbi Yakov Breisch (Chelkas Yakov-3:57) notes that this differs from the normal approach to kashrus certification, where a Rav Hamachshir may adopt leniencies corresponding to the majority of consumers he is targeting, as individuals who want to be machmir will simply avoid using the product. Mikvaos must be built to highest possible standards, to service the most pious individuals, as they do not have the option to refrain from using the mikvah.
ZECHILAH
The advent of municipal tap water over two hundred years ago provided opportunity to build more accessible mikvaos, which could be cleaned and heated. In earlier days, the most expedient way of mikvah construction was to dig deep down to access natural water and thus they avoided זחילה, flowing rainwater, one of the major issues which can invalidate a mikvah. Mikvah translates as ‘a gathering of water’ and Mikvaos-1:7 notes that rainwater mikvaos must have stationary water, whereas in spring mikvaos flowing water is permitted. Despite this major advantage, these ancient spring mikvaos had serious drawbacks. One had to climb flights of precarious dark stairs to reach the mikvah, which also made it difficult to transport boiling water to heat the freezing cold mikvah water. There was no way of cleaning the pool after multiple use unless the spring water self-cleaned itself. Every town was built near a river, so an alternative solution might be to dip in river water – does that avoid zechilah?
OCEANS RIVERS AND LAKES
Mishnayos Parah-8:8 and Mikvaos 5:4 debate whether seas have the zochalim problem, as the Torah calls the seas ‘mikvah’, but rivers flow into the seas like mayan. Shulchan Aruch (YD-201:5) rules that oceans are treated like spring water regarding the din of zechilah and moving seas are not problematic, but oceans are considered a mikvah regarding zav, metzora and parah adumah which need a higher level of purity and require “mayim chaim”. Whether rivers are considered like flowing springs or not is debated in Shabbos 65b, as rivers generally are fed by both rainwater and underground springs. Rav determines each river’s status based on which type of water constitutes most of the river at any given time. If the majority is rainwater or spring thaw, then the flowing zechila would invalidate the river. One can measure the impact of rain by observing the size of the river before the rainy season and attributing any growth to rainfall. Thus, the same river might be a ma’ayan during a drought and lose this status after a downpour. However, Shmuel’s cryptic statement: נהרא מכיפיה מיברך ‘that a river grows from its rocks’, is interpreted by Rashi to mean that a river is increased primarily from its source, from springs in its bedrock. Tosafos queries that we can see that the river experiences enormous swelling during the rainy season and the spring thaw, which would indicate that to be the primary source. Tosafos answers, based on Taanis 25b, that the greater part of this enlargement is generated by the river’s feeder springs, which match any rainwater with intensified flow during this season. Rishonim debate which opinion to follow, and Maharik (115) compromised to allow immersion in parts of the river that flowed even before the enlargement, as that original section clearly came from natural springs. Shulchan Aruch (YD-201:2) rules against immersing in rivers under any circumstances. Rema records the custom of communities located far from any mikvah who use rivers in accordance with Rabbeinu Tam in any area of the river, and one should not object to this practice in those circumstances, but he otherwise agrees with the Mechaber.
LATER AUTHORITIES
However, Shach restricts Rema’s leniency to areas which were originally known to be spring fed and not in locations of seasonal expansion. Aruch Hashulchan (YD-201:42) justifies immersion in rivers in isolated areas far from a mikvah following Rema, but one should avoid areas enlarged from their original flow in accordance with Shach. Tzemech Tzedek (Miluim-5:30) writes of remote Russian towns where they permitted immersion using heated boxes in freezing rivers. Poskim are reluctant to be lenient nowadays with the greater availability of travel. There is also now a totally different reason why lakes and rivers might be invalidated, because many rivers have dams with metal sluice gates which control the water level and flow of water. The waters of Lake Kineret are regulated by the Degania Dam, whose lifting sluice gates are mekabel tumah vessels which hold up the entire lake water. Dams have turbines which generate electricity from water energy and are vessels which possibly invalidate water passing through them to the river below. Freshwater lakes have complications similar to rivers. The exact situation regarding water source being spring or rainwater, and whether there is outflow, has to be examined before asking a shaaloh.
KASHERING MUNICIPAL WATER
Tap water is regarded by poskim to be considered sheuvim, drawn water because it passes through vessels such as filters, meters and invalid pipes. The only viable solution to changing mikvah water is to be able to utilise tap water, so one must be able to kasher the water somehow. Halacha has three ways of converting sheuvim into kosher rainwater, which form the basis for modern mikvah construction – hamshachah, zeri’ah and hashakah.
HAMSHACHAH
The process of hamshachah consists of pouring invalid water on the ground outside the mikvah, which then flows naturally into the mikvah. Temurah 12a records that if a mikvah contains over twenty sa’ah of valid rainwater, then R’ Eliezer ben Yakov permits obtaining the rest of the forty sa’ah by running invalid sheuvim along the ground into the mikvah. Some wanted to suggest that a complete mikvah could be created through hamshachah, but Rambam (Mikvaos-4:9) rejects this view. Tosafos here (d.h.michlal) asserts that a mikvah comprised entirely of sheuvim revitalised through hamshachah is only rabbinically disqualified. Shulchan Aruch (YD-201:44/6) rules that hamshachah flowing over three tefachim of any ground-type is effective when running into over twenty sa’ah of valid rainwater. Mordechai (Shevuos/Mikvaos) explains that when sheuvim flow over absorbent ground, it becomes part of the earth and is rejuvenated as groundwater. Rema quotes this opinion that it must flow over three tefachim of absorbent earth. Modern mikvaos pass all water entering a mikvah along a hamshachah channel, and in order to give the earth permanence, they use concrete, leading to a debate among poskim if concrete is absorbent. Many therefore specify to use pervious concrete with a higher percentage of sand to gravel for this purpose. Whilst hamshachah reduces sheuvim to a rabbinic level, it cannot be used to fill an entire mikvah, and for that we also employ the techniques of zeri’ah and hashakah.
ZERI’AH
Once a mikvah contains at least forty sa’ah of kosher rainwater, one may add an unlimited amount of invalid water without affecting its kashrus. Moreover, the added water is halachically transformed from sheuvim into kosher rainwater. Contemporary mikvaos use this technique by constructing a reservoir filled with rainwater next to the immersion pool and then any tapwater added to fill the pool is first passed through this rainwater reservoir. This process is called zeri’ah, meaning planting, because the added tap water is conceptually sown into a body of natural water and sprouts as freshwater, losing its sheuvim status, just as a seed achieves new status when it grows.
HASHAKAH
Hashakah, meaning ‘kissing’, refers to the technique of unifying two bodies of water when they touch each other. If one constructs another rainwater reservoir, called bor hashakah, adjacent to the immersion pool, separated by a common wall, any invalid water in that pool can be validated by the waters meeting through a hole in the partition. Mikvaos-6:7 specifies the size of hole required to merge the two containers as ‘shefoferes hanod’, the opening of a container, a diameter that fits two fingers. R’ Moshe Feinstein (IM-YD2:89) recommends the hole to be three inches. A removable plug is placed in the hole so that the rainwater in the bor hashakah does not get sucked out when the immersion pool water is changed. After the two pools have merged, an opinion cited by Rabbeinu Yerucham (26:5) requires that the hole between them remains open at the time of immersion. Shulchan Aruch (YD-201:52) rules like other opinions which hold that the tap water becomes permanently purified, but many take out the plug at the time of immersion.
