intended to increase the knowledge, interest, and anticipation of the reader, thereby hastening the realization of our hopes and prayers for the rebuilding of Jerusalem and the Beit HaMikdash.

Mikdash Mikva'ot - Ritual Baths (II)
While the building of a valid Mikvah which meets the complex Halachic requirements is exceptionally complicated and requires the supervision of experts in the field, the basic principles of its construction are not difficult to comprehend. A Mikvah is comprised of two parts, a storage cistern - the Otzar HaMayim or BorHaMayim - and the actual immersion pool which is connected to the Otzar HaMayim by a pipe. A tank containing 40 Se'ah of water (Pesachim 109, et al), roughly 922L (opinions vary), is the minimum size required for the Otzar HaMayim. The source for the initial 40 Se'ah must be rainwater or spring water that is routed directly into the Otzar HaMayim. It is essential that the water flowing into the Otzar HaMayim pass through pipes and conduits which have no receptacles, impediments, encumbrances or traps where water might collect ("stand") and thereby invalidate the Mikvah. Water piped in this manner is considered Halachically "natural" water and therefore is deemed suitable for the initial 40 Se'ah of water contained in the Otzar HaMayim. An easily accessible filter (the Halachot here can be tricky) positioned and firmly fixed to the end of the pipe strains out unwanted residues. Once the Otzar HaMayim holds the required 40 Se'ah of "natural" water, "ordinary"water from other sources can be diverted into it. (The two sections of the Mikva'ot in the Mikdash in all likelihood were waterproofed with lime mortar so that they retained the collected water.) Over the millennia the initial source of "natural" water for most Mikva'ot came from rainwater that fell on the roof of the building which housed the Mikvah. The same principle - although on a much larger scale - was also operative in the Beit HaMikdash. It is likely that the initial 40 Se'ah of the Mikva'ot in the Mikdash and those located on Har HaBayit came from both aqueducts and rainwater.

The Structure of a "Rainwater" Mikvah
(1) Rain falls on the slanted roof of the Mikvah building. The rainwater is directed to (2) a hole in the roof leading to a pipe which conveys the water to the (3) the Otzar HaMayim - the Mikvah reservoir. When at least 40 Se'ah of rainwater have fallen into the Otzar HaMayim, the entry pipe is closed preventing the entry of additional rainwater. "Ordinary" water (4) can then be added to the Otzar HaMayim. The source of this water is not restricted. As water enters the Otzar HaMayim, the level rises reaching the conduit (5) connecting the Otzar HaMayim with the Mikvah Immersion Pool (6). When the Mikvah immersion pool reaches the proper level, the conduit is plugged with a bung stopping the water flow. The ritually impure person descends the stairs (7) and immerses. When a person immerses the water level rises (8).

The Mikvah immersion pool is always constructed in close proximity to the Otzar HaMayim. The minimum size of a Mikvah immersion pool is one Amah square and three Amot deep (Chagiga 11a, et al) but it could be and usually is considerably larger since it has to be deep enough to enable the water to cover the entire body of the person immersing. When the water stands in the Otzar HaMayim, silt and other impurities sinks to the bottom leaving clean water; only pure water flows into the Mikvah immersion pool. The minimum diameter of the slanting connecting pipe which permitted water to flow from the Otzar HaMayim to the Mikvah immersion pool of conduit is one Tefach (approx. 5cm), although these pipes are also usually larger.

In building a valid Mikvah, the intent of the construction workers is crucial. The Mikvah has to be built with the intention that it is to be used as a Mikvah - for purification - and not merely as a bath or hygienic purposes. The Otzar HaMayim, the Mikvah immersion pool, and the connecting pipes may not be made of material which is susceptible to ritual impurity such as metal. The accouterments of the Mikva'ot of the Mikdash were constructed of stone or concrete which were not subject to ritual impurity. Similar Mikva'ot from the Mikdash era have been recently excavated in the "houses of the Kohanim" in the "Upper City (a.k.a. the "Jewish Quarter") and under Yeshivat HaKotel. (There are two methods in building a Mikvah, which vary in some particulars. The method described and pictured above is called Hashaka ("touching"). The other method is called Zeri'a ("seeding") which is beyond the scope of this column. Both methods have been used over the centuries and the Rishonim are divided in their preferences. Rambam and the Ra'avad prefer Hashaka. Rashi, Rabbeinu Tam, Rosh, Tur, Ramban and Rashba maintain that "Zeri'a" is preferable. In choosing Hashaka over Zeri'a to illustrate the basic principles of Mikvah construction, we make no pretense of deciding practical Halacha.When lions contend, let the field mice beware! And truthfully it is difficult to say which method was used in the construction of the Mikva'ot of the Mikdash. In Israel today, most Mikva'ot - except for Chabad's - are now built using two Otzrot HaMayim - thus allowing a combination of both methods.)

Periodically, the Otzar HaMayim and the Mikvah immersion pool have to be be cleaned. The water is totally removed and the interior of both structures thoroughly dried. Once dried and cleaned, the Otzar HaMayim is again filled with 40 Se'ah of "natural" water and then "ordinary" water added. The water level rises until water spills through the connecting conduit and refills the Mikvah immersion pool. <to be continued>

Catriel is in the process of writing a book: The Temple of Jerusalem, A Pilgrims Prospective; A Guided Tour through the Temple and the Divine Service.