Last week's issue discussed the basic construction of a mikveh. A basic mikveh may be halachically suitable for immersion, but over the course of time, the mikveh will accumulate dirt and bacteria and will not be practically suitable for immersion. The challenge of constructing a mikveh that is available to the public is to find a halachically suitable method of changing the water in the mikveh (or adding water to it) on a regular basis. One must keep in mind that as discussed in last week's issue, drawn water is invalid for a mikveh and that precipitation in most areas is not consistent enough to allow one to refill the mikveh with rain water on a regular basis. This week's article will discuss some of the methods employed to produce a hygienic and halachically valid mikveh.

The Two Prevalent Methods
There are two basic methods employed to allow the mikveh to be filled with drawn water. Both methods involve collecting rain water in a reservoir and then using a second immersion pool that receives its validity from the reservoir.

One method is zeriah (literally planting). The source for zeriah is the Mishna, Mikva'ot 6:8, that states that if there are two adjacent wells, one which already contains the requisite forty se'ah of water and the other is empty, it is permissible to continue pouring drawn water into the full well, and allow it to overflow into the empty well until that well also fills up with water. Rashi, Pesachim 34b, s.v. Mei HaChag, explains the concept of zeriah that water that enters a mikveh becomes part of the mikveh. Placing water into a mikveh is the equivalent of planting a seed. The Mishna, Terumot 9:7, states that ritually impure seeds that were planted become pure once they sprout. Therefore, the concept of zeriah allows one to purify the drawn water by pouring it into the original reservoir and allowing the overflow to fill the actual immersion pool.

The second method employed is hashakah (literally kissing). The Mishna, Mikva'ot 6:3, states that if a well of drawn water is connected to a valid mikveh, the well of drawn water becomes valid. The Mishna, Mikva'ot 6:7, states that two adjacent wells can be connected if the wall between them has a hole the size of a sh'foferet hanod (the mouthpiece of a leather bottle). The Mishna describes this hole as having a diameter of the width of two fingers. Based on the concept of hashaka, if one constructs the actual immersion pool adjacent to the original reservoir and puts a hole in the wall that separates the two areas, the immersion pool can be filled with drawn water and then purified by the reservoir of rain water.

The Validity of Relying on Zeriah Alone
There is one potential problem with relying on zeriah as a method of transforming drawn water into mikveh water. The Mishna, Mikva'ot 7:2, states that if one "adds one se'ah and removes one se'ah" the mikveh is valid. The Gemara, Yevamot 82a, states that if one does this for the majority of the water, the mikveh is invalid. Most Rishonim understand that the Gemara is referring to a case where one replaces the water with fruit juices. If one adds some fruit juice to a complete mikveh, the mikveh is valid, but if majority of the mikveh is composed of fruit juice, the mikveh is invalid. However, Rambam Hilchot Mikva'ot 4:7, and Ra'avad, Sha'ar HaMayim 1:5, are of the opinion that the Gemara refers to a case where one adds drawn water to a valid mikveh such that majority of the mikveh is drawn water. Shulchan Aruch, Yoreh De'ah 201:24, follows the majority opinion that this concern only applies to fruit juices. Nevertheless, Shach, Yoreh De'ah 201:63, recommends that one should be concerned for the opinion of Rambam and Ra'avad that this invalidity applies to drawn water.

As such, relying on zeriah presents a problem. After one or two times of overflowing the original reservoir, majority of the reservoir will contain drawn water. This should, ostensibly, present a problem according to Rambam and Ra'avad. [Chazon Ish, Likutim L'Hilchot Mikva'ot 3:2, notes an important difference between Rambam's opinion and Ra'avad's opinion. He notes the comment of Kesef Mishneh, Hilchot Mikva'ot 4:7, that Rambam is concerned that replacing mikveh water with drawn water will look like the entire mikveh is composed of drawn water. However, Ra'avad seems to be of the opinion that there is a fundamental problem with replacing most of the mikveh water with drawn water. Chazon Ish suggests that Rambam will only invalidate a mikveh if the water of the mikveh is removed and replaced by drawn water. If one merely adds drawn water to a mikveh, Rambam will not invalidate the mikveh. Ra'avad invalidates the mikveh even if no water is removed.]

Does Hashakah Provide the Solution?
If one is concerned for the opinion of Ra'avad, hashakah should, ostensibly, provide a better solution. However, executing hashakah properly may present the same problem as zeriah. There is a dispute regarding the method of hashakah. According to Rabbeinu Asher, Teshuvot HaRosh 31:2, it is sufficient to connect the original reservoir with the immersion pool for only a moment. Rabbeinu Yerucham 26:5, disagrees and maintains that hashakah is only valid while the two bodies of water are connected. If the hole connecting the two bodies of water is sealed, the immersion pool that was filled with drawn water is invalid as a mikveh. Shulchan Aruch, Yoreh De'ah 201:52, rules in accordance with the opinion of Rabbeinu Asher. However, Shach, Yoreh De'ah 201:112, recommends following the stringency of Rabbeinu Yerucham.

If the hole connecting the two bodies of water remains open on a permanent basis, the water from the two bodies of water will eventually mix together. This will pose the same problem that zeriah poses- that according to Ra'avad, a mikveh is invalid if it is composed of majority rain water, regardless of its original composition. The logical way, then, to implement hashakah would be to place a stopper in the hole and only open the hole momentarily when the immersion pool is refilled with drawn water. However, this does not satisfy the opinion of Rabbeinu Yerucham.

There are a number of suggestions to solve this dilemma. These suggestions ultimately determine the way a mikveh is constructed. First, R. Moshe Feinstein, Igrot Moshe, Yoreh De'ah 1:111 (and 1:109), rules that both the opinions of Ra'avad and Rabbeinu Yerucham are minority opinions and therefore, zeriah and hashakah are valid according to the letter of the law. However, if the resources are available, one should build two reservoirs, one to perform zeriah and one to perform hashakah. The reservoir used to perform hashakah should contain a plug that is only opened momentarily. By removing the plug only momentarily, one prevents the drawn water from entering into the reservoir used for hashakah. This will satisfy the opinion of the Ra'avad. Although, it does not satisfy the opinion of Rabbeinu Yerucham, the zeriah will be sufficient to satisfy his opinion. [R. Feinstein, ibid, 1:112, notes that the opinions of Rabbeinu Yerucham and Ra'avad cannot coexist, and therefore, using both methods will guarantee a valid mikveh according to all opinions.]

R. Shalom Dovber Schneerson (the sixth Lubavitcher Rebbe, cited in the addendum to the Otzar Chassidim edition of Shulchan Aruch HaRav Vol. V-VI) offers a different solution to this problem. He suggests placing the reservoir directly underneath the immersion pool. R. Schneerson claims that the difference in temperatures between the immersion pool and the reservoir will limit the transference of water between the two bodies of water. At the same, the reservoir can constantly be replenished with rain water and the "overflow" will end up in the immersion pool. These two factors ensure that a high rate of rain water remains in the original reservoir. R. Schneerson's suggestion is the model for the current mikva'ot built by Chabad.

R. Yoel Teitelbaum (The Satmar Rebbe), Divrei Yoel, Yoreh De'ah no. 79, provides a solution that combines R. Feinstein's solution (which was already prevalent before R. Feinstein) and R. Schneerson's solution. R. Teitelbaum suggests using both the zeriah and hashakah methods, but with one addition. The reservoir that is used for hashakah is double the requisite size (eighty se'ah) and is divided in half by a wall that has a hole the size of a sh'foferet hanod. That reservoir, in essence, becomes a double-decker reservoir, where the top reservoir connects to the immersion pool. The rationale for this construction is that the lower reservoir is less likely to contain a majority of drawn water. That reservoir will continuously remove any invalidity of the upper reservoir (according to Ra'avad) which in turn will do the same for the immersion pool. By doing this, one gains the advantage of R. Feinstein's approach as well as the advantage of R. Schneerson's approach.