1)

(a)The Mishnah discusses water that overflows from vessels that have been placed at the foot of a drainpipe into a Mikvah. It is not Pasul anyway due to its having flowed down the drainpipe - because we are discussing a wooden drain-pipe that was fixed before being carved, which is not considered a K'li (see Tiferes Yisrael).

(b)The Tana - declares the water Mayim She'uvin.

(c)He draws no distinction between (very) large vessels and (very) small ones. He sees fit to mention ...

1. ... large vessels - even though they are so large that they are not subject to Tum'ah (see Tos. Yom-Tov).

2. ... small vessels - even though they are too small to be subject to Tum'ah [Ibid.]).

(d)He also lists vessels made of dung (or of marble), of stone or of earth. We might otherwise have thought that the water will remain Kasher - seeing as they are not subject to Tum'ah.

2)

(a)Beis Shamai declare the water Pasul, irrespective of whether the vessel was placed there on purpose or it was forgotten there. Beis Hillel - declare it Kasher in the latter case.

(b)The Gemara in Shabbos establishes the case - where the owner placed the vessels there when the sky was overcast, but forgot to collect them after the clouds dispersed ...

(c)... and they are arguing over - whether the scattering of the clouds automatically cancels the owner's initial intention (Beis Hillel) or not (Beis Shamai).

(d)Had the owner ...

1. ... forgotten the vessels there after the clouds dispersed - Beis Hillel would concede that the water is Pasul, whereas, had he ...

2. ... placed the vessels there whilst the sky was clear - Beis Shamai would concede that the water is Kasher.

3)

(a)According to R. Yossi, the Machlokes between Beis Shamai and Beis Hillel was never resolved. R. Meir maintains - that Beis Hillel retracted (see Tos. Yom-Tov).

(b)The Halachah - is like R. Yossi (see Tos. Yom-Tov).

(c)The Mishnah also rules that if the owner forgot the vessels (not under a drainpipe, but) in the middle of the Chatzer - the Mikvah is Kasher, even according to Beis Shamai (see Tiferes Yisrael).

4)

(a)Now the Mishnah discusses a board that is placed at the foot of a drainpipe - to transmit the water from the pipe to an adjoining Mikvah.

(b)The water is not considered Mayim She'uvin - provided the board does not have a rim on all four sides (see Tos. Yom-Tov).

(c)If the owner stood up the board to drain, but water from the drainpipe still managed to reach the Mikvah via it - the Tana rules that, either way, the water does not invalidate the Mikvah ...

(d)... because the water did not enter the Mikvah via a receptacle (see also Tos. Yom-Tov).

5)

(a)The Mishnah rules that water flowing through a regular pipe is not Mayim She'uvin - because the pipe is not a receptacle.

(b)For the water to become Mayim She'uvin from now on - one needs to carve a cavity into the pipe to catch stones and the like, to prevent them from falling out at the other end.

(c)This ruling must be confined to a pipe that was carved out before being fixed - because only then does it have the Din of a K'li. If on the other hand ...

(d)... it is fixed first - then the cavity will be part of the Mikvah, and will not fall under the category of Mayim She'uvin.

6)

(a)The smallest cavity in a wooden pipe renders the water Mayim She'uvin. An earthenware one, says the Tana Kama - requires a cavity that holds a Revi'is ...

(b)... because less than that, an erthenware vessel is not sufficiently Chashuv to be considered a K'li.

(c)According to R. Yossi - neither requires a Shi'ur ...

(d)... and the Revi'is that the Tana Kama heard was said in connection with the shards of a broken earthenware vessel (which are only considered a K'li if they hold a Revi'is.

(e)The Halachah is - like the Tana Kama.

7)

(a)The Mishnah discusses what the Din will be if in the aforementioned cavity there are Tzeroros ha'Mischalchelin (pebbles that roll around) or Afar ha'Nechbash - earth that has been packed tight [like a street] see Tos. Yom-Tov).

(b)The Tana rules - that ...

1. ...Tzeroros ha'Mischalchelin - do not alter the status of the pipe, whereas

2. ... Afar ha'Nichbash - negates from it the Din of Mayim She'uvin ...

(c)... since, whereas in the former case, water passing through the pipe still seeps into the cavity, in the latter case it merely runs over it.

8)

(a)The Tana, discussing a pipe that is narrower at the ends and wider in the middle, forming an automatic cavity, switches here from Tzinor to Si'lon - which are essentially one and the same (see Tos. Yom-Tov DH 'ba'Tzinor').

(b)He rules that such a pipe - does not render the water that passes through it Mayim She'uvin ...

(c)... because the cavity was not made to serve as a receptacle (see Tos. Yom-Tov).

9)

(a)If Mayim She'uvin and rain-water mix in the Chatzer before falling into a large pit (making up forty Sa'ah), the Mikvah will be ...

1. ... Kasher - if the majority is rain-water, but ...

2. ... Pasul - if the majority is Mayim She'uvin.

(b)Twenty-one Sa'ah of rain-water is considered a majority (see Tos. Yom-Tov).

(c)If it comprises half of each - the Mishnah declares it Pasul.

(d)The Tana issues the same ruling if the two mix ...

1. ... on the steps leading to a cave, or ...

2. ... in an Uka ...

(e)... a hole in the ground).

10)

(a)Until now, the Tana has been speaking about the two waters that mixed before flowing into the pit. In the event that the Mayim She'uvin falls into rain-water that is already in the pit however - three Lugin will render an incomplete Mikvah Pasul (as we have already learned a number of times).

(b)Less than twenty-one Sa'ah of Mayim She'uvin will not however, render the Mikvah Pasul even if it falls into nineteen Sa'ah of rain-water - if it falls into it by means of Hamshachah (it first flows three Tefachim along the ground [See Tos. Yom-Tov]).

11)

(a)When the Mishnah disqualifies water that one has draws from a trough (see Tiferes Yisrael) that is carved into a rock - it is referring to water that one intends to use for Mei Chatas (for the Parah Adumah).

(b)The Tana also disqualifies the trough itself from Kidush - from being used as a K'li for mixing the ashes of the Parah Adumah with the spring-water that preceded it.

(c)One is also not permitted to sprinkle the Mei Chatas that one poured into it on to the Tamei person or objects.

(d)The reason for the two latter rulings is - because both of them require a K'li, and a trough is not considered a K'li, since it is attached to the ground.

12)

(a)When the Tana adds ve'Einah ...

1. ... Tzerichah Tzamid Pasul, he means that - if it situated in a covered area where a Meis is lying, it need not be sealed in order to protect whatever is inside from Tum'ah.

2. ... Poseles es ha'Mikvah, he means that - if three Lugin of water that flows from it into an incomplete Mikvah, it will not invalidate it.

(b)The ...

1. ... trough will be considered a vessel in all the above regards however - if it was carved before being attached to the ground.

2. ... vessel will subsequently lose its status of K'li (and not render the water in it Mayim She'uvin) - if it sprung a leak ...

(c)... in the bottom or at the side near the bottom, in a way that it cannot hold any water ...

(d)... irrespective of the (small) size of the hole (see Tos. Yom-Tov).

(e)For Mayim She'uvin in one pit to become Bateil to a full Mikvah in an adjoining pit (and therefore be considered a Kasher Mikvah) - the hole in between must be ki'Shefoferes ha'Nod (that a person's fore and middle fingers can swivel round in it.

13)

(a)R. Yehudah ben Beseira relates an episode regarding Sho'kes Yeihu in Yerushalayim - a trough that served as the main Mikvah in the city for Toveling Taharos.

(b)Its irregular feature was that - it did not contain forty Sa'ah, but was joined to a Mikvah which did, by means of a hole that measured ki'Shefoferes ha'Nod.

(c)Beis Shamai - went and enlarged the hole, until most of the height (Tiferes Yisrael) of the dividing wall was split ...

(d)... because otherwise, the trough still had the Din of a K'li (see Mishnah Achronah).