Mikvaos 6:10-11

Mikvaos 6:10

If the drain of a bathhouse mikvah is in the center, it invalidates the mikvah but if it’s on the side, it doesn’t because then it’s like one mikvah adjoining another; this is the opinion of Rabbi Meir. The Sages say that if the basin can hold a quarter-log before the water reaches the drain, the mikvah is valid; if such is not the case, it’s invalid. Rabbi Elazar bar Rabbi Tzadok says that if the drain can hold any amount of water, the mikvah is invalid.

Mikvaos 6:11

Regarding the “washing off” pools in a bathhouse, let’s say the lower was full of drawn water and the upper was full of valid mikvah water. If there are three log opposite the opening between the two pools, the upper is invalidated as a mikvah. Rabbi Yosi says the opening must be 1/320th the size of the pool in order to hold three log. Rabbi Elazar says that even if the lower pool is full of valid water and the upper pool is full of drawn water and there were three log by the opening, the lower pool is valid because the Sages only said “if three log fell in” (i.e., drawn water doesn’t invalidate a mikvah through contact alone).