Purifying a Mikveh

Mikvaot (3:2) | Yisrael Bankier | 9 years ago

Over the course of the week we have been learning about cases where drawn water is added to a mikveh. We have learnt (3:2) that if a mikveh contains water that is less than the minimum amount required (forty seah) and three log of water falls into the mikveh, it is invalid.  The Mishnah teaches how one remedies the situation.  The first solution is that one is required to effectively empty the mikveh of all its water.  The second solution is that if there is a kosher mikveh in the same courtyard just below the first, then one is able to “metaher” it. How so? 

The Bartenura explains that we connect the two mikvaot via a stream of water in order that their waters connect, enabling the tahor mikveh to metaher the pasul one. He explains that this works through the principle of gud asik. This requires further explanation. 

Gud asik is a principle more commonly found in the laws of partitions. There, if a wall is ten tephachim high, the minimum height of a wall, it is considered as if it extended upward. Here, it appears that the principle of gud asik is being used to bring the two mikvaot close together.

The Tifferet Yisrael questions the necessity of gud asik. Since the solution is working by way of the principle of hashakah – causing the contact of the invalid water with the kosher mikveh– that alone should be a sufficient explanation. He answers that hashakah functions based on zeriya (Pesachim 34b) – literally “planting”. The Mishnah teaches later (6:8) that if one has a kosher mikveh and below it an empty pit, one can draw water and pour it into the kosher mikveh thereby causing water to spill over into the empty bit below resulting in a second kosher mivkveh. The Bartenura there explains that since the upper kosher mikveh has more than forty seah, adding drawn water does not invalidate it. The water that spills over is therefore valid mikveh water. 

He explains that since hashaka is built on zeriya, for hashaka to work the two mikvaot need to be adjacent to one another.  In our case they are a distance apart and only connected by way of the stream that flows between them.  Gud asik is therefore required to halachically bring the two mikvaot together. 

The Tifferet Yisrael however raises another question. We learnt previously (Taharot 8:9) that a nitzuk (flow) or ketafres (incline) is not considered a connection.  Our Mishnah appears to go against that principle since it seems we are relying on nitzuk to metaher the bottom mikveh. 

He first brings an answer on the name of his father who differentiates between the two Mishnayot. In the Mishnah in Taharot, nitzuk does not combine two bodies of water because there they are both less than the minimum size and we need them to combine to make a kosher mikveh. In our case however, we are trying to achieve something different; we already have a kosher mikveh. In our case we are trying to metaher a mikveh and nitzuk works. 

The Tifferet Yisrael however elaborates further. He explains that there is a more fundamental difference between the two cases.  The minimum size of a mikveh is biblical in origin. Consequently, we are stricter in that case and discount the use of nitzuk. In our case however the issue of drawn water is rabbinic. This fact affords is the leniency of using nitzuk. 

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