DAYS OF NIDAH (according to the Torah)
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(a) Day one starts with the first sign of menses. Seven days of Nidah ensue, in which she is prohibited to her husband and has the status of an Av HaTumah. She can bleed the entire seven days. On the night of the eighth day if she does not experience bleeding the woman goes to the Mikvah and becomes Tehorah, starting the eleven days of Zivus.
DAYS OF ZIVAH (according to the Torah)
mikvah
1
2
3
4
5
6
7
8
9
10
11
(b) The eleven days, that follow the seven days of Nidah, are "days of Zivah."
Example of Zavah Ketanah
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3
11 Mikvah
Shomeres Yom k'Neged Yom 4
(c) If a woman experiences bleeding during these days for one or two consecutive days, she becomes a Zavah Ketanah and is Temei'ah. She is prohibited to her husband & has the status of an Av HaTumah. If she does not experience bleeding the following night and day, she may immerse in a Mikvah during the day to become Tehorah. She may even immerse on the morning immediately following the day on which she experienced bleeding, but her Tumah and Taharah are contingent upon whether or not she experiences bleeding afterwards on that day. She is called a Shomeres Yom k'Neged Yom, because she must watch the following day to confirm whether or not she experiences bleeding.
Example of Zavah Gedolah
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3
4
(d) If a woman experiences bleeding for three consecutive days during her eleven days of Zivah, she becomes a Zavah Gedolah. In order for her to become Tehorah, she must count "Shivah Neki'im”, seven "clean days" in which she experiences no other bleeding. On the morning of the seventh day, she immerses in a Mikvah. If she does not experience bleeding during the rest of the day, she is Tehorah and is no longer a Zavah. A Zavah Gedolah also must bring a Korban Zavah to permit her to enter the Beis haMikdash or to eat Kodshim. This Korban is two Torim or two Benei Yonah, one offered as an Olah and one as a Chatas (VaYikra 15:25-30).
(e) After the 18th day (7 of Nidah and then 11 of Zivus), she can no longer become a Zivah in this period of time. At the next sighting of blood, the process starts over as a Nidah.
Example of Bleeding on the Eleventh Day
11
(f) In the matter of “only” bleeding on the 11th day in the cycle for Zivus, it is not possible to become Zavah Gedolah. Nevertheless, she observes all the laws of Shomeres Yom k'Neged Yom.
Example of Nidah Nowadays
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8 1 9 2 10 3 11 4 12 5 13 6 14 7
(g) Nowadays, Jewish women accepted upon themselves a double stringency: all menses blood in whatever time period are considered Nidah, and afterwards requires 7 clean days prior to going to Mikvah.
