Mikvaos 3:1-2

Mikvaos 3:1

Let’s say that there were two mikvahs, neither of which contained 40 seah, and a log and a half of drawn water fell into each, after which the two mikvahs got mixed together. In such a case, Rabbi Yosi says that the mikvahs are valid because they had never been declared invalid. However, if there’s a mikvah of less than 40 seah and three log of drawn water fall into it, after which it was divided into two smaller mikvahs, they are invalid because the original mikvah was already designated invalid. Rabbi Yehoshua rules them valid because he maintains that any mikvah of less than 40 seah (about 140 gallons) into which three log of drawn water falls (about 42 ounces) and from which a kortov was then removed (1/64 of a log – about 0.2 ounces) is rendered valid because the three log have also been reduced. The Sages, however, say that the mikvah remains forever invalid until its original volume plus a little extra is removed.

Mikvaos 3:2

Continuing from the previous mishna: Let’s say that there was a cistern in a courtyard and three log of drawn water fell into it. The mikvah will remain forever invalid until all of its original volume is removed, plus a little more, or until another mikvah of 40 seah is established in the courtyard (and connected to the existing mikvah) so that the higher water (in the cistern) can be made valid by the lower water (in the mikvah). Rabbi Elazar ben Azariah declares the water in the cistern invalid unless the connections to the old, invalid mikvah are closed.