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How much water do you need in a mikvah?

by Rabbi Yossi Marcus


Library » Women & Judaism » Women's Mitzvot » Family Purity | Subscribe | What is RSS?


Immersion in a Mikvah must be total and all-encompassing. The entire body must be submerged at one time in the water. The mikvah must therefore be at least one square cubit by three cubits high.1 This equals 40 “se’ah” (about 100 gallons) of water.2

From a mystical perspective, the number 40 is significant in rebirth. Forty is the number signifying the span of time necessary for creation: In the development of an embryo, the human form is established after forty days.3

So after immersing in the mikvah, the convert becomes "like a baby just born," a new being. Similarly, it is customary to immerse in a mikvah before the onset of Shabbat, recreating ourselves for Shabbat when we become “new” people.

The 40 se'ah of the mikvah bring about a rebirth for one who immerses in it.

The flood of Noah served as a cosmic mikvah that purified the world--hence the 40 days of rain, paralleling the 40 se'ah of water necessary for a Kosher mikvah. Indeed, after the flood, Noah "beheld a new world."


  • 1. A cubit is an ancient measurement (Amah) the approximate equivalent of 1.5 feet (18 inches/46 centimeters).
  • 2. Talmud tractate Pesachim 109b
  • 3. Talmud, Bechorot, 21b


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Life Cycle » Marriage » Family Purity » The Laws

(pl: Shabbatot). Hebrew word meaning "rest." It is a Biblical commandment to sanctify and rest on Saturday, the seventh day of the week. This commemorates the fact that after creating the world in six days, G-d rested on the seventh.
Literally means "fit." Commonly used to describe foods which are permitted by Jewish dietary laws, but is also used to describe religious articles (such as a Torah scroll or Sukkah) which meet the requirements of Jewish law.
A ritual bath where one immerses to become spiritually pure. After her menstrual cycle, a woman must immerse in the Mikvah before resuming marital relations.
Tenth generation from Adam. Of all humankind, only he and his family survived the Flood which destroyed all civilization in the year 2106 BCE.