When Does the Count of the Seven Clean Days Begin?

When exactly does the count of the seven clean days begin? The whole article is practical halachah.

The basic rule — the count begins the day after the hefsek

The seven clean days begin on the day after the day of the hefsek taharah. (In rare situations they may begin several days after the day of the hefsek.)

It's critical to understand that under no circumstances can the seven clean days begin on the same day as the hefsek taharah (see the earlier articles for the sources).

Why does this matter so much?

Unfortunately this is a common mistake, and a fairly serious one. If a woman mistakenly began counting seven clean days from the day of the hefsek taharah and then immersed, her immersion is not valid.

A woman who discovers she made this mistake should seek halachic guidance on how to proceed.

An example — the count made clear

Suppose a woman performs a hefsek taharah on Sunday before sunset:

She will immerse on Sunday after nightfall, the point at which the seventh day of the count has been completed.

A way to remember

Some women find this helps: whichever day of the week the hefsek taharah was performed on, that is the day of the week she will immerse.

For example:

• A woman who performed a hefsek on Monday before sunset will immerse on Monday after nightfall.
• A woman who performed a hefsek on Tuesday before sunset will immerse on Tuesday after nightfall.
• And so on.