Tevilah in a Mikveh on Erev Yom Kippur:[1]

A. The custom:

It is customary to immerse in a Mikveh on Erev Yom Kippur to purify oneself.[2]

When should one go to the Mikveh?[3] One should immerse in the Mikveh prior to Mincha in order to say the confession prayer in purity. However, some are accustomed to immerse after the Seudas Hamafsekes[4] in order to immerse as close as possible to Yom Kippur. [In the Siddur, Admur rules one is to immerse in the Mikveh prior to Mincha. Practically, it is the custom of Chassidim to immerse at both times.[5]]

How many times should one immerse within the water?[6] This depends on the reason behind the immersion. According to the reason that the immersion is done to purify oneself from the state of Keri, only one immersion within the water is necessary. However, according to the reason that the immersion is done as a symbol of Teshuvah, one is to immerse three times.[7] [Practically, one is to immerse three times.[8]]

Q&A

Must one shower and remove Chatzitzas prior to immersion?[9]

Although during the regular year it is not required to remove a Chatzitza from the body prior to immersion[10], nevertheless, regarding the immersion of Erev Yom Kippur one must verify that his body contains no intervals during the immersion. Thus, one is to remove every item from his body, and clean himself of any dirt. One is to cut his hand nails, and if his toe nails are long, he is to also cut the nails of his feet. This is not to be done the same day. One is to comb through his hair to remove any knots, and is to brush his teeth prior to this immersion.

A watch: Some[11] write that initially one is to remove from the body all items that one normally removes upon bathing. Accordingly, one is to initially remove a tight watch from his arm prior to immersion [and so is the custom]. A loose watch however is not required to be removed.

Clothing: Some[12] write based on the above ruling that initially one is to remove tight clothing from his body prior to immersion [and so is the custom]. Loose fit clothing however is not required to be removed.

Bandage/Cast:[13] If one is unable to remove it, then he may immerse with the bandage or cast on his body. [If it is prohibited to be immersed in water, one may place a tight plastic bag over it.]

Ear plugs:[14] One who may not allow water to enter his ears due to medical reasons may immerse using ear plugs or cotton balls and the like. 

Dreadlocks in the beard:[15] Dreadlocks is not considered an interval.

 

If one did not cut neither his toe nor hand nails before Erev Yom Kippur, may he cut them both on Erev Yom Kippur?

Some Poskim[16] rule one is to only cut his hand nails while the toe nails should be thoroughly cleaned. Others[17] however rule that in such a situation one may cut both nails on the same day, even if he is particular about this during the rest of the year.[18]

 

Must one immerse his entire body in the Mikveh?[19]

Yes. Even one’s hair must be completely submerged within the water. If even one strand of hair was protruding from the water the immersion is invalid for Keri.

 

Taking a shower after Mikveh:

It is permitted for men to take a shower after Mikveh[20], although some are stringent not to do so.[21] Nevertheless, on Erev Shabbos [and Erev Yom Tov] according to all it is better not to do so, in order so one not completely wash off the Mikveh water from his body, as will be explained next.

Drying oneself after Mikveh:[22]

Based on the teachings of the Arizal, one should not dry the Mikveh water off his body after immersing.[23] Practically, we are particular to dry ourselves with a towel after immersion and one who desires to follow the directive of the Arizal is to leave some part of his body undried.[24] It suffices for one to leave his feet wet in order to fulfill this directive.[25]

B. Should women immerse on Erev Yom Kippur?[26]

Women are accustomed to immersing in a Mikveh on Erev Yom Kippur.[27] This custom is followed even by virgins, [and other single women who are above the age of Mitzvos, and certainly applies for married women]. [However, some Poskim[28] vehemently oppose unmarried women immersing in a Mikveh, as doing so can lead to promiscuity.]

Married women who are within three days of marital relations:[29] A married woman who is within three days of having marital relations, then if she had relations in close proximity to her Mikveh night or her expected period, then she is not to immerse in a Mikveh on Erev Yom Kippur.[30] [See footnote[31]] If however, she is within three days of relations that did not take place in proximity of her immersion or her period, then she may immerse on Erev Yom Kippur. Prior to her immersion, she is to thoroughly clean out her vaginal area with hot water in order to expel all the seed from her body.[32] Women who are not within three days of marital relations are not required to clean themselves from possible semen prior to the immersion.

Q&A

Should single women and girls immerse on Erev Yom Kippur?

This matter is disputed amongst Poskim, as mentioned above, and there are different customs followed amongst communities.[33]

Should married women who are impure immerse?

It is permitted [and accustomed] for married women to immerse in a Mikveh on Erev Yom Kippur even if they are impure, and within Shiva Nekiyim.[34] Some[35] however write that a woman who is within her 7 clean days is not to immerse.[36]

May a woman who is after Shiva Nekiyim, but has still not immersed in a Mikveh, immerse on Erev Yom Kippur?

Some Poskim[37] rule she may immerse and have in mind to not be Yotzei the Mitzvah of immersing for her husband. This will allow her to immerse later on for her husband with a blessing. Others[38] suggest that she is to immerse on Erev Yom Kippur with a Chatzitza on her body.

C. If a Mikveh is not available:[39]

Introduction:

The immersion in a Kosher Mikveh accomplishes two matters. It purifies a person from the Keri impurity and it adds extra purity to the soul, cleansing it in a form of Teshuvah [i.e. Tosefes Taharah].[40] According to many Poskim[41] these two aspects and benefits are independent of each other and receive separate laws in a case that a Kosher Mikveh is not available. Regarding the purification from Keri, the Sages established that a Kosher Mikveh is not required and hence the immersion in drawn water or pouring of nine Kavim is valid, [as will be explained below]. However, regarding the purity added to the soul, these forms of Mikveh are invalid.[42] Hence, one is always to prefer a Kosher Mikveh over using the methods below and the methods below are to only be used when there is lack of alternative.[43] On the other hand, there is also a stringency regarding the purification of a Baal Keri over the aspect of Tosefes Taharah, as the Poskim bring that in a time of need one may pour water over the hands or learn Mishnayos to accomplish the Tosefes Taharah. It however does not help to purify one from the state of Keri. [See Q&A for details on this topic]

Using Mayim Sheuvim-swimming pool:[44] To achieve purification from the state of Keri one may immerse in 40 Seah [90 gallons or 332 liters[45]] of even drawn water that is in the ground [such as a typical swimming pool].[46] However, it does not help to immerse in a vessel that contains drawn water.[47] [An over the ground swimming pool is seemingly invalid for this purpose.]

Nine Kavim-shower:[48] If one is not able to immerse in any body of water [even a swimming pool and the like] then he is to pour nine Kavim [12.5 Liters[49]] of water over his body. One may use up to 2 or 3 buckets of water for this purpose, pouring each bucket one after the other, if in total they contain nine Kavim of water. In such a case, one must begin pouring the second bucket prior to finishing the pouring of the first bucket, and so too one must begin pouring the third bucket prior to finishing the pouring of the second bucket. It is invalid to use four buckets of water for the accumulation of nine Kavim, [and hence if the first three buckets or last three buckets do not contain nine Kavim in total it is invalid].[50] Even when pouring from one vessel one must be careful that the water continuously falls on him without any interval at all. If one entered halfway into a Mikveh and on his top half he poured nine Kavim, it is valid. [See Q&A regarding shower]

If it is painful for one to immerse in the Mikveh or he is sick:[51] If it is painful for one to immerse in a Mikveh [such as the water is too cold[52], or one is sick] then he may follow the method brought above of pouring nine Kavim of water. [However, one should not initially choose pouring nine Kavim over immersing in a Mikveh, as the nine Kavim only accomplish the removal of the Keri impurity. It however does not accomplish the additional purity added by immersing in a Mikveh.[53]]

Washing the hands forty times in a case that one is unable to immerse in a Mikveh or shower: See Q&A!

Q&A on Sheuvim

Can one fill up his bathtub and immerse in the water for purification of Keri?[54]

It is only valid to do so if: a) the hole of the bathtub is at least 3.8 centimeters wide[55], and b) one is able to stop up the hole, and c) it is filled with 332 liter of water, and d) one is able to fully immerse his entire body within the water simultaneously. [Typical bathtubs are not large enough to accomplish this by a normal sized person.]

 

Q&A on Nine Kavim

Can one perform “nine Kavim” in the shower?

Yes.[56] One can do so by staying under the shower head for 3-4 minutes consecutively without turning the water off for even a moment in between.[57] One is to stand straight under the shower head with his hands weakly folded over his chest as explained next. It is invalid to do so while one is lying in the bath, as will be explained.

How is the nine Kavim to be poured over the body?[58]

The water must be poured over the entire body. One is to stand straight with his hands weakly folded over his chest[59] or along his sides down to the thigh[60] and have the water poured directly over his head. It is not necessary that the water actually touch every part of the body.[61] Nevertheless, some Poskim[62] rule that one is to wet his feet beforehand in order so the water being poured attaches to the water under his feet. It however does not have to touch the armpit and the like.[63] It is not valid if the water was poured only on one part of the body, even if one later pours on the other part.[64] However, there are Poskim[65] who are lenient in such a case.

Does a Chatzitza/interval invalidate the nine Kavim?[66]

One must remove all intervals from the body prior to pouring the nine Kavim.

Does it help to immerse in nine Kavim?[67]

No. The nine Kavim are only valid if they are poured onto the person and not when one immerses in them. This applies whether the water is in the ground or in a vessel. If, however, it contains 40 Seah in the ground then it is valid for immersion.

Lying in a bath and having the nine Kavim [shower] poured over his body:[68]

The nine Kavim are only valid if they are poured over his entire body, as stated above. Thus, it is invalid for one to sit or lie in a bathtub with water and have the nine Kavim poured over his head.[69]

Other alternatives to a Mikveh

Washing the hands forty times in a case that one is unable to immerse in a Mikveh or shower:

If one is unable to immerse in a Mikveh or shower with nine Kavim then he should purify his hands by pouring water on them forty times.[70] The order is as follows: One first pours ten times on each hand, alternating between each hand after each pour.[71] One then pours ten times consecutively on the right hand and ten times consecutively on the left hand for a total of 40 pours between the two hands combined.[72] The 40 acts of pouring correspond to the 40 Seah of a Mikveh.[73] One is to intend the Divine 72 letter name [שם ע”ב], which is found in the Divine name of Havaya, during these pourings.[74] [The Rebbe states[75] that these pouring only give a person the additional purity that the immersing in a Mikveh accomplishes, however it does not remove the Keri impurity from the body.]

Learning Mishnayos:[76]

One who is unable to immerse in a Mikveh is to learn Mishnayos that deal with the laws of Purity. This especially applies to Miseches Mikvaos. Nevertheless, this only gives a person the additional purity that the immersing in a Mikveh accomplishes, however it does not remove the state of Keri impurity from the body.

If one immersed in a pool or performed nine Kavim should he also pour forty times on his hands or recite the Mishnayos?

Seemingly, one is to do so in order to gain the additional purity received from these washings.[77]

General Q&A

Is Zochlin[78] invalid for a man’s Mikveh?

Many Poskim[79] rule that a Mikveh which is Zochlin is invalid for purification of the state of Keri.[80] Others[81] however rule that it is valid for purification from the state of Keri.

May a man immerse in a Mikveh with a filter?

*For proper understanding of the terms and ruling below refer to the next supplement for all the details and clarifications on this matter.

It is best for a man to immerse in a Mikveh that is valid [at least Bedieved] even for women and Keilim, in order to benefit from both purification of Keri and Tosefes Taharah according to all opinions.[82] Regarding filters: If the filter does not pose an issue of Zochlin or Sheuvim [see supplement for different types of filters and their law] then it is valid according to all. Many men Mikvaos today use a tube filter that is submerged within the water on the basis that it does not pose a problem of Sheuvim or Zochlin.[83]  In the event that the Mikveh uses a filter that poses a problem of Zochlin or Sheuvim, it is best to immerse in a different Mikveh that does not contain a problematic filter. This applies even if the filter is currently turned off, nevertheless if it poses a problem of Sheuvim it is best to immerse in a different Mikveh.[84] However Bedieved, or in a time of need, one is not to refrain from immersing in such a Mikveh.[85] In the words of the Minchas Yitzchak[86], “certainly one is not to be stringent [by a men’s Mikveh] all the stringencies taken by a women’s Mikveh, especially if one does not have anywhere else to immerse”.

 

May a man immerse in a Mikveh while it is being filled with water?

Yes.[87] However it is a Hiddur to avoid doing so.[88]

May a man immerse in a Mikveh while it is being emptied of its water?[89]

No.[90] However in a time of need one may certainly immerse in such a Mikveh and he receives reward for doing so.

May one initially use a swimming pool as a Mikveh?[91]

If a Kosher Mikveh is available, one is not to immerse in a swimming pool. This applies even if the pool does not contain a filter.[92] If a Kosher Mikveh is not available, one may immerse in the pool, making sure to turn off the filter prior to doing so.[93] If one is unable to turn off the filter, he is nevertheless not to refrain from immersing in the pool if there is no other Mikveh available.[94]

 

May men immerse in a women’s Mikveh?[95]

Some Poskim[96] rule men may even initially immerse in a woman’s Mikveh and we do not assume this will detract woman from visiting the Mikveh.[97] Practically men are not to immerse in a women’s Mikveh if there is a men Mikveh available. If another Mikveh is not available it is permitted to immerse in a woman’s Mikveh if doing so will not cause women to be deterred or challenged in going to this Mikveh as a result of the men’s immersion. If, however, one has established that there are women who are disturbed by this matter then the men may not immerse in the Mikveh.[98] However regarding Erev Rosh Hashanah and Erev Yom Kippur it can be arraigned for the men to immerse[99], although care should be taken to switch the waters afterwards and clean the Mikveh in anticipation for the woman’s immersion.[100]

Summary-If no Mikveh is available:[101]

If one does not have a Mikveh available he can immerse in any ocean or sea. If this too is not available one can immerse in even immersed water such as a swimming pool. If one is not able to immerse in any body of water then he is to pour nine Kavim of water over his body. [One can do so by staying under the shower head for 3-4 minutes.[102] If one is unable to shower then he should purify his hands by pouring water on them forty times.[103] The order is as follows: One first pours ten times on each hand, alternating between each hand after each pour.[104] One then pours ten times consecutively on the right hand and ten tomes consecutively on the left hand for a total of 40 pours between the two hands combined.[105]]

Sparks of Kabala

The Kavanos while immersing in a Mikveh:[106]

One is to immerse eight times in the Mikveh, each time with a different Kavana. The first time one immerses he is to intend that he is immersing in a Mikveh Taharah which is the Gematria of 151 which corresponds to the name Eh-Yeh. This purifies one from his impure state. The second immersion is to rectify one’s bad trait of anger. The third immersion is to rectify the blemishes he created in Sheim Ab. The fourth immersion is to rectify the blemishes he created in Sheim Sag. The fifth immersion is to rectify the blemishes he created in Sheim Mah. The sixth immersion is to rectify the blemishes he created in Sheim Ban. The seventh immersion is to remove the weekday garments of the soul. The eighth immersion is to receive the ray of Yom Tov, of Yom Hazikaron. These Kavanos likewise apply on Erev Yom Kippur.

The purification affected by a Mikveh:[107]

There is a tradition from the Kabalists that there are four hundred aspects of impurity that reside upon an impure person. In order to remove these 400 aspects of impurity one must immerse in a Mikveh of 40 Seah. The waters represent Chesed and hence have the ability to purify the body. One’s entire body must be immersed in the Mikveh simultaneously as if even one hair is protruding from the water the impurity remains on that hair and then spreads to the rest of the body [upon coming out of the water].

__________________________________

[1] Admur 606/11

[2] The reason: There are two reasons mentioned behind the immersion. Some write it is done in order to purify oneself from the state of Keri. Others write it is done as a symbol of Teshuvah. [Admur ibid]

[3] Admur 606/13; M”A 606/10; Mateh Efraim 619/3

^[4] Assuming there still is time remaining in the day.

^[5] Shevach Hamoadim; Hence one immerses three times of on Erev Yom Kippur: 1. Before Shacharis, 2. Before Mincha, 3. After the Seudas Hamafsekes.

One who is unable to immerse these amount of times: Regarding these numerous immersions, and what to do if one is unable to immerse this many times, it is told of Rav Levi Yitzchak Schneerson, the Rebbe’s father, that when he was only able to approach a Mikveh one time on Erev Yom Kippur he immersed several times in the Mikveh, getting dressed between each time, in order to fulfill the custom of immersing several times of Erev Yom Kippur. [Days of awe days of Joy p. 159]

[6] 606/11-12

[7] As this symbolizes that the person has done Teshuvah and is now reborn as a new person. [ibid]

[8] Beir Heiytiv 581/16; Mateh Efraim 606/8; and so is implied from Admur 606/12 that the custom is to immerse also for Teshuvah purposes.

[9] Mateh Efraim 606/8; Alef Lamagen 606/17 in name of Machazikei Bracha and Sefer Haeshkol; Ben Ish Chaiy Netzavim 3; Kaf Hachaim 581/84; This is also required based on the teachings of the Arizal. [Kaf Hachaim 260/4]

[10] Eshkol [Tefila 1]; Mamar Mordechai [1790] 1-2, brought in Shaareiy Teshuvah 88/1; Biur Halacha 88 “Vechen”; Shulchan Melachim in Halacha Lemoshe Dinei Tevilas Ezra 12; Piskeiy Teshuvos 88/8; Leaning opinion of Minchas Chinuch 180/4

Other Opinions: Some Poskim rule that a Chatzitza invalidates the immersion of a Baal Keri. [Amudei Eish Kuntrus Beis Tefila 12; opinion of Gadol brought in Minchas Chinuch 180/4] The Shaareiy Teshuvah ibid leaves this matter in question. The Ashel Avraham Tinyana [Butchach] 88 implies that initially one should remove a Chatzitza [The statement brought in Piskeiy Teshuvos ibid footnote 57 that the Ashel Avraham holds it does not even contain a Midas Chassidus is inaccurate] The Rashba [Yevamos 47] rules that a Chatzitza invalidates the immersion of a Baal Keri. Nevertheless, this only refers to one who needs to immerse Biblically, such as in the times of the Temple. However, for the immersion of Takanas Ezra even the Rashba agrees it is not necessary. [Shulchan Melachim ibid]

[11] Piskeiy Teshuvos 88/8; Vetzrauch Iyun on his source as the simple reading of the Poskim ibid do not imply that a differentiation exists between forms of Chatzitzas.

[12] Piskeiy Teshuvos 88/8; Vetzrauch Iyun on his source as the simple reading of the Poskim ibid do not imply that a differentiation exists between forms of Chatzitzas.

[13] Piskeiy Teshuvos ibid

[14] Piskeiy Teshuvos ibid

[15] Ashel Avraham [Tinyana] 88

[16] Mateh Efraim 606/8

[17] Alef Lamagen 606/18

[18] As even during the rest of the year many Poskim rule there is no need to avoid cutting both pairs of nails on the same day. Hence, certainly on Erev Yom Kippur for the sake of avoiding having a Chatzitza one may do so. [ibid] See “The Laws and Customs of Erev Shabbos” Chapter 1 Halacha 17 Q&A.

[19] Piskeiy Teshuvos 88/8

[20] Sheivet Halevy 7/33; Piskeiy Teshuvos 88/8; Even regarding a Niddah the Rama Yoreh Deah 202/75 rules that only some opinions are stringent and so is the custom. However, others argue on Rama and rule doing so is permitted even by a Niddah. [See Gr”a ibid; Darkei Teshuvah 202/332; Lechem Vesimla 122]

[21] Piskeiy Teshuvos 260/1 in name of Sheivet Halevy that so is the custom of the world to avoid doing so despite it being allowed from the letter of the law. See also Tiferes Adam 1/28 which rules one should never shower after Mikveh.

[22] Based on Kaf Hachaim 260/8

[23] As the water is considered holy with the spirit of Shabbos [and Yom Tov] and it is thus proper for the body to absorb it. [ibid] However see Kaf Hachaim 260/8 who writes that this only applies if one did not immerse more than once, otherwise he has already washed away the main Mikveh water. Nevertheless, he concludes that even the second waters of the Mikveh has some holiness and is thus not to be dried.

[24] The holiness of that leftover water from the Mikveh will then subsequently spread to the rest of the body. [Rebbe Shaareiy Halacha Uminhag 1/131]

[25] Shaareiy Halacha Uminhag 1/131

[26] Admur 606/11-12; M”A 606/8; Mateh Efraim 606/8; M”B 606/21

Other customs: Women of Sefaradic origin are not accustomed to immerse on Erev Yom Kippur. [Nittei Gavriel 18/9 footnote 19]

[27] The reason: This custom is based on the reason mentioned above that the immersion is done for purposes of Teshuvah, which is of course applicable to both men and women equally.

[28] Sdei Chemed Yom Kippur 1/6, brought in Alef Lamagen 606/16

[29] Admur 606/11; See Piskeiy Teshuvos 607/9 for other opinions in this regard

[30] The reason: As these are times when she can become pregnant and the water can destroy the semen, and prevent the pregnancy. The explanation is as follows: A woman who is within three days of marital relations must wash her vaginal area prior to Mikveh using hot water in order to remove any semen, as if the semen is expelled within three days of relations, she returns to become ritually impure. However, when a woman is within three days of relations that is near her time of fertility, she cannot wash herself out as it will destroy the semen. Therefore, there is no need at all for her to immerse, as she may in any event return to become impure on Yom Kippur. [Admur ibid] The implication from Admur ibid is that only hot water, which a woman within three days of marital relations must wash her inner parts with is what, is forbidden during times auspicious for pregnancy. However, the actual immersion in cold water does not pose an issue.

[31] The above ruling in Admur 606/11 is recorded in continuation of the opinion who rules that the entire purpose of the immersion on Erev Yom Kippur is for Keri purposes. Vetzaruch Iyun if according to the second opinion [brought in Admur 606/12] who rule the immersion is for Teshuvah purposes, even these women are to immerse, and are thus arguing on this point as well. On the other hand, perhaps the second opinion is only arguing on the amount of times one is to immerse, and the custom for even non-married women to go. Vetzaruch Iyun.

[32] As otherwise their entire immersion may be useless, as if they expel seed within three days they return to become ritually impure. [Admur ibid]

[33] See Nitei Gavriel 18/9 footnote 20 who writes that while Besulos do not immerse, divorcees and widow’s do immerse. Regarding the Chabad custom: I heard from Harav Eliyhu Landa that the custom by us is that Besulos do not immerse, and so I heard from Harav Braun of Crown Heights.

[34] Rav Poalim 4/16; Levushei Mordechai 1/123; Sugah Beshoshanim 28/4; Minchas Yitzchak 6/146; Nitei Gavriel 18/10

[35] Shiureiy Shevet Halevi and Koveitz Mibeis Levi 4/20; Rav Asher Lemel Cohen

[36] The reason: As this can lead to them having relations prior to the proper time.

[37] Minchas Yitzchak 6/146

[38] See Nitei Gavriel 18/11 footnote 22

[39] 606/11 regarding Erev Yom Kippur

[40] Shalah Hakadosh Yuma p. 288; Minchas Yitzchak 3/64; Kinyan Torah 1/33; See Igros Kodesh 9/353; Igros Kodesh brought in Shulchan Menachem 1/143; Igros Kodesh Rebbe Rayatz 2/142 distinguishes between the two matters regarding pouring and Mishnayos.

[41] Shalah ibid; Minchas Yitzchak ibid; Kinyan Torah brought in previous footnote; Implication of Admur 606/10 “And this Tevila which is due to Baal Keri is permitted even with Mem Seah of drawn water and Nine Kavim”

Other Poskim: Some Poskim are lenient and rule that the leniencies of Sheuvim [and Zochlin] apply even when one immerses for Teshuvah or Tosefes Taharah. [Torah Leshma 375; Munkatcher in Divrei Torah 9/83; Piskeiy Teshuvos 88/6] Nevertheless, even the above Poskim are initially stringent [Darkei Chaim Veshalom 356; Piskeiy Teshuvos ibid]

[42] Shalah ibid; Minchas Yitzchak ibid; Kinyan Torah ibid; Implication of Admur 606/10 “And this Tevila which is due to Baal Keri is permitted even with Mem Seah of drawn water and Nine Kavim”

[43] Kinyan Torah 1/33; Piskeiy Teshuvos 88/4; and so is implied from Admur 606/11-see previous footnotes.

[44] Admur 606/11; 88/1

[45] Shiurei Torah 3/29

Other Opinions: According to the Chazon Ish 40 Seah is 576 liters.

[46] As this immersion for the purpose of purifying oneself from the state of Keri is valid even when using drawn water. [ibid]

[47] Admur 606/11; 88/1 [in parentheses]; M”B in name of Rav Akiva Eiger; Stringent opinion in Gemara Brachos 22b; See Piskeiy Teshuvos 88 footnote 44 for a discussion on this matter.

Other Opinions: There is an opinion in the Gemara ibid who rules a vessel is valid for a Baal Keri.

[48] Admur 88/1; 606/11; Taz 88/1; Olas Tamid 88/2; M”A 606/9; Elya Raba 606/11

[49] Shiurei Torah 3/30 writes that 9 Kavim is equivalent to 12.441 liters of water. The Piskeiy Teshuvos 88/5 writes that according to the Grach Naah [author of Shiurei Torah] one is to initially use 18 liters and 12.5 litters is only in a time of need. Vetzaruch Iyun as to his source, being that the Grach Naah explicitly writes 12.5 liters.

Other Opinions: The Chazon Ish rules that initially it is to be 23 liters and in a time of need 17.5 liters suffice. Others rule it is 11.3 liters. [brought in Piskeiy Teshuvos ibid] Others rule it is 16 Liters. [Minchas Yitzchak 4/51]

[50] Admur ibid; Some Poskim [Bier Heiytiv 88] record 3-4 buckets are valid. This is a printing error. [Kaf Hachaim 88/6]

[51] Admur 606/11 regarding Erev Yom Kippur; However, in 88/1 Admur plainly rules that a Baal Keri can even initially perform nine Kavim and does not limit this to one who is sick. Seemingly the reason is because everyone agrees that nine Kavim remove the Keri impurity however it does not purify a person like a Mikveh for purposes of Teshuvah, and since some opinions rule one immerses Erev Rosh Hashanah and Erev Yom Kippur for purposes of Teshuvah, it is only to be used as a last resort. [See Kinyan Torah 1/33]

[52] M”B 581/26

[53] Kinyan Torah 1/33; Piskeiy Teshuvos 88/4; and so is implied from Admur 606/11-see previous footnotes.

[54] Divrei Yichezkal 13; Piskeiy Teshuvos 88 footnote 44

[55] Shiurei Mikveh p. 163 [However Lechatchila it is to be 4.8 cm wide]

The reason: This is the measurement required for an item to not be considered a vessel.

Other Opinions: According to the Chazon Ish Shefoferes Hanod is 4.8 cm wide.

[56] Kinyan Torah 1/33; Tzur Yaakov 9; Chelkas Yaakov 3/61 Minchas Yitzchak 4/51; Vayaan Yosef 1/45; Divrei Yaatziv Likkut 13; Beir Moshe 6/74; Shraga Hameir 1/16; Sheivet Halevi 1/24; Piskeiy Teshuvos 88/5

Other Opinions: Some Poskim are stringent and disqualify the use of a shower on the basis that according to the Raavad one requires Koach Gavra to validate the nine Kavim. [Opinion of Mishneh Halachos 3/2-6; 3/8; 5/19-22; 6/23]. The vast majority of Gedolei HaPoskim ibid however rule it is allowed based on that we do not rule like the Raavad in this matter, and even according to the Raavad today that the nine Kavim is only a custom he would agree it is allowed. [Kinyan Torah ibid]

[57] Piskeiy Teshuvos 88 footnote 42 [This applies even according to the opinion who requires 23 liters]

[58] M”B 88/4; M”E 606/10; Kaf Hachaim 88/7

[59] So is implied from Mateh Efraim ibid; M”B ibid that state “Neged Libo” and that it should not be “a forceful hug”.

[60] Kaf Hachaim 88/7

[61] Alef Lamateh 606/3; However see P”M 88 M”Z 1 who learns from the Rambam that the water must touch every area of the body. Nevertheless, the P”M himself concludes that the custom is not to do so. See Eretz Tzvi 1/89; Shaareiy Teshuvah 88/1 in name of Mamar Mordechai

[62] P”M 88 M”Z; Kaf Hachaim 88/7

[63] Piskeiy Teshuvos 88/5, and so is proven from the P”M ibid which does not require to wet it beforehand.

[64] Beir Moshe 5/18

[65] Rav Shlomo Kluger in Shiyurei Taharah brought in Piskeiy Teshuvos 88/5 footnote 38

[66] Alef Lamateh 606/3; Eretz Tzvi 1/89; Piskeiy Teshuvos 88/5

[67] Admur 88/1; M”B 88/4 in name of Beis Yosef; Piskeiy Teshuvos 88/5

[68] Mateh Efraim 606/12; Unlike ruling of Divreiy Yisrael 1/11 brought in Piskeiy Teshuvos 88 footnote 40

[69] This is unlike the case stated in Admur ibid that it is valid to pour the nine Kavim on the upper part of the body when the lower part is in the Mikveh, as that law only applies by a Kosher Mikveh and not to the water in a bathtub. [M”E ibid]

[70] Ben Ish Chaiy Netzavim 3 based on Sefer Emes Leyaakov; Kaf Hachaim 76/22; Ashel Avraham Butchach 88; Rav Mottle Chernobyl brought in Sefer Chesed Leavraham; Piskeiy Teshuvos 88/4; Igros Kodesh 9/353

[71] Thus, the first pour is on the right hand, the second on the left, the third on the right etc until by the 20^th pour each hand received ten pours inconsecutively.

[72] ibid

[73] See Kaf Hachaim ibid; Piskeiy Teshuvos 88 footnote 31

[74] The following is the Kavana: The name Havaya when written in full [with the unseen pronounced letters] contains 10 letters (יו”ד-ה”י-וי”ו-ה”י). These ten letters equal the Gematria of 72. Prior to beginning the pouring one is to supplicate to G-d and say “May it be Your will that this washing of the hands be considered as if I immersed in 40 Seah of a Mikveh…. “One is then to pour on the right hand one time  intending the first letter “Yud” he then pours on the left hand one time also intending the first letter “Yud”. He continues intending each letter for each pouring of right-left for a total of ten letters, each letter being intended by each set of right left pourings. He is then to pour ten times consecutively on the right hand intending one letter of the Divine name by each pouring. He then repeats this order for the left hand. [Emes Leyaakov brought in  Kaf Hachaim ibid]

[75] Igros Kodesh 9/353

[76] Igros Kodesh brought in Shulchan Menachem 1/143; Igros Kodesh Rebbe Rayatz 2/142

[77] As explained above that the Nine Kavim or Mayim Sheuvim only help to remove the Keri impurity and not for Tosefes Taharah which is accomplished through a Mikveh.

[78] A Mikveh that contains water that is flowing from it is defined as Zochlin.

[79] Mechzeh Avraham 13 based on M”A 159/27 and Admur 159/22 as explained in Machatzis Hashekel 159 regarding Tevilas Yadayim for bread; Zichron Yehuda 2/62; Vayaan Yosef 46; Beir Moshe 5/21; Minchas Yitzchak 3/64; Piskeiy Teshuvos 88/6

[80] The reason: They rule that Zochalin [running water] is invalid for purification of a Baal Keri just like it is invalid for a Halachically required immersion [i.e. Niddah; Ger; Vessels]. [Yoreh Deah 201/2] The proof that Zochlin is invalid for Keri is from the fact the Machatzis Hashekel ibid explains that the reason the Raavad is lenient to allow immersing hands in 40 Seah of drawn water [see Michaber 159/16; Admur 159/23] is because it is valid for a Baal Keri. Thus we see that regarding Zochlin, it is invalid even for a Baal Keri and therefore even regarding Tevilas Yadayim there is question as to whether it is valid. The reason to differentiate between Sheuvim and Zochlin, that Sheuvin is valid while Zochlin is not, is because according to most Poskim Zochlin is a Biblical requirement while Sheuvim is only Rabbinical, and hence by a Baal Keri we are lenient only regarding Sheuvim. [Beir Moshe ibid]

Zochlin Sheiyno Nikeres: Some Poskim rule one may be lenient regarding an unnoticeable flow [such as a crack in the wall] regarding Tevilas Ezra. [Beir Moshe ibid]

Zochlin above 40 Seah: Some Poskim rule one may be lenient regarding a flow that occurs above the 40 Seah water level of the Mikveh regarding Tevilas Ezra. [Beir Moshe ibid]

Water going into the Mikveh: Some Poskim rule one may be lenient regarding a flow of water that enters into the Mikveh regarding Tevilas Ezra. [Beir Moshe ibid]

[81] Arugos Bosem brought in Teshuvah of Zichron Yehuda, brought in Minchas Yitzchak 3/64

[82] Minchas Yitzchak 3/64; Kinyan Torah 1/33; Mishneh Yosef 4/3; Piskeiy Teshuvos 88/6 [that initially one is to use a Mikveh that is Kosher with all the Hidurim].

[83] Mikveh Mayim p. 84 and p. 17; Beir Moshe 5/21; Piskeiy Teshuvos 88/6 footnote 43

Background and other opinions:

Such a filter is not an issue of Zochlin according to all as the water never leaves the Mikveh. [Mikveh Mayim p. 84 and p. 17; Piskeiy Teshuvos 88/6; Beir Moshe ibid] Likewise if the filter is made in a way that it does not hold the water but is simply a tube with filtering material that the water passes through, then it also does not pose an issue of Sheuvim. [ibid] Nevertheless many of today’s Poskim forbid such a filter for a women’s Mikveh due to Zochlin. [Kol Korei in Kisleiv 5767; Brought in Kuntrus Mikveh Al Gabei Haotzer of Rav Boaz Lerner p. 59] Likewise these filters can also pose a problem of Sheuvim due to their filtering cloth. [ibid]

[84] As according to many Poskim Sheuvim is only valid for Keri and not for Tosefes Taharah.

[85] As Sheuvim is valid according to all to purify from Keri and Zochlin itself is a dispute if valid for Keri, and it is also disputed whether the filters we use today are at all defined as Zochlin even for a woman’s Mikveh. Hence one is certainly not to refrain from immersion due to a problematic filter.

[86] 3/64; so rules also Beir Moshe 5/21

[87] Beir Moshe 5/21; This matter is disputed in Poskim regarding whether it is considered Zochlin. [See supplement on men immersing in a Mikveh with a filter.] The Beir Moshe ibid concludes that one may be lenient regarding a Baal Keri.

[88] As some Poskim rule it is considered Zochlin. [See supplement on men immersing in a Mikveh with a filter.]

[89] Beir Moshe 5/21; Piskeiy Teshuvos 88 footnote 48

[90] As the Mikveh is considered Zochlin.

[91] See Minchas Yitzchak 3/64; See Piskeiy Teshuvos 88/6 which states that a pool is [even initially!] valid even if its filter is working. This is not fully accurate as explained in the supplement and footnotes below. Nevertheless in a time of need certainly one is not to refrain from immersing in a pool with a filter.

[92] As pools are mostly made of Sheuvim, which is invalid for Tosefes Taharah according to many opinions, as explained in the introduction above, and the next supplement. Furthermore, even according to the lenient opinions mentioned there, they agree that it is proper to initially immerse in a Mikveh that is valid even for women.

[93] In order to avoid the problem of Zochlin according to all.

[94] As according to some Poskim the filters used in pools are not considered Zochlin. [See Supplement and Piskeiy Teshuvos 88/6] Furthermore according to some Poskim Zochlin is valid for a Baal Keri. See supplement on men immersing in a Mikveh with a filter.

[95] Igros Moshe Yoreh Deah 2/90; See Shut Rav Mordechai Eliyahu 24 in answer to a question posed by a Balanit of a women’s Mikveh

[96] Shoel Umeishiv Telisa 1/123

[97] He states that there that this is the custom in many cities that the men and women use the same Mikveh and there was never a protest regarding this matter. In the city of Prague the men, including the Rav and his Beis Din all used the women’s Mikveh. Furthermore there is actually benefit in this as the men, who understand the laws of Mikveh, will be able to visit and determine the Kashrus status of the Mikveh and fix any problems that may have occurred over the years. See there for the fierce wording used against those who want to forbid men from going to a woman’s Mikveh under the basis that it deters the women from going.

[98] Igros Moshe ibid; Shut Rav Mordechai Eliyahu ibid

[99] Igros Moshe ibid that so was the arraignment made in the Mikveh in Detroit.

[100] Shut Mordechai Eliyahu ibid

[101] 606/11

[102] Piskeiy Teshuvos 88 footnote 42

[103] Ben Ish Chaiy Netzavim 3 based on Sefer Emes Leyaakov; Kaf Hachaim 76/22

[104] Thus the first pour is on the right hand, the second on the left, the third on the right etc until by the 20^th pour each hand received ten pours inconsecutively.

[105] ibid

[106] Kaf Hachaim 581/83

[107] Chesed Leavraham Mayan 2/59