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Sefer Hamitzvosספר המצוות

Day 238: Positive Commandment 109

Monday, 17 Tishrei 5787 / September 28, 2026

Positive Commandment 109 (Digest)

Immersing in a Mikvah (Ritual Pool)

"He shall bathe all his body in water"—Leviticus 15:16.

A person who chooses to become cleansed of any ritual impurity is commanded to immerse in a mikvah [a natural pool of water]. According to the tradition of the Oral Law, for a mikvah to be kosher it must contain enough water for [an average] person to submerge himself within them—unless it is a moving stream of water, in which case even the smallest amount of water suffices [for a smaller than average individual, or for immersing a ritually impure utensil].

Some details:

* Of all the types of ritually impure people, only the zav requires immersion in a moving stream of water.

* This mitzvah is not obligatory. As long as an individual has no intention of entering the Temple Mount, he may remain in his ritually impure state.

* An individual's purification process is not finalized until the sun sets on the day he immerses.

* There may not be anything separating between the person's body and the waters of the mikvah.

Unabridged English Text of this Mitzvah »

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> The 109th mitzvah is that we are commanded to immerse in the waters of a mikvah and thereby be purified from whichever form of tumah previously existed.

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> The source of this commandment is G‑d's statement;) (exalted be He), "He must immerse his entire body in water." The Oral Tradition;) explains that [the phrase "his entire body" also teaches that] there must be enough water to cover his entire body.;) This is the minimum size of a mikvah unless the water is from a spring, in which case there is no minimum amount,;) as explained in the laws which deal with this mitzvah.

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> Among the conditions [governing the mikvah] is that only in the case of a zav is spring water required,;) as the verse;) states, "mayim chaim."

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> When we say that immersion is a mitzvah, this does not mean that any person who is tameh is required to immerse himself — as one who wears a four-cornered garment must put tzitzis on it, or that anyone with a house must build a fence around the roof. [When I say, "it is a mitzvah,"] I refer to the laws of immersion — that we are commanded that anyone who wants purification from tumah can do so only through immersion in water, after which he becomes tahor.

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> The Sifra;) says, "One might think that the phrase;) 'He must immerse in water' is a Divine decree [and that it is an absolute requirement to immerse]. The verse therefore says, 'then he can return to the camp' [after being purified] from tumah." This hints to the principle I just explained, i.e., that the mitzvah is just the law, i.e., that one who wants to be purified should take certain steps. This law is itself the mitzvah. This does not mean however, that there is an independent requirement to immerse — should he want to remain tameh and not enter the machaneh Shechinah;) for any period of time, he may do so.

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> The Book of Truth (i.e., the Torah) explains that even though after the person immerses he becomes tahor, his purification is incomplete until sunset.;) The Oral Tradition also explains that during immersion he must be naked and that his entire body must come in contact with the water. As our Sages put it,;) "The phrase, 'his entire body' teaches that there can be nothing intervening between his body and the water."

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> We have therefore explained that this mitzvah of immersion includes the laws of mikvah, of intervening substances, and t'vul yom.;) This mitzvah is explained in tractates Mikva'os and T'vul Yom.

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> Footnotes

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> Lev. 15:16.

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> Sifra.

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> This is 40 se'ah of water.

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> In practice, even a mikvah of spring water must contain 40 se'ah.

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> In other cases, even for a zavah, rain water is sufficient.

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> Lev. 15:13.

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> Ibid., 16:26.

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> Ibid., 14:8.

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> Corresponding to the Temple courtyard.

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> See Lev. 22:6. A person in this state is called a t'vul yom.

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> 11.

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> Eruvin 4b.

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> 12.

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> One who has immersed and is awaiting sunset, as mentioned above.

Courtesy of Chabad.org · Sefer Hamitzvot, Sichos in English

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