Mikvaos 4:3-4

Mikvaos 4:3

Let’s say that someone made a cavity in a rain spout to catch the gravel. In the case of a wooden rain spout, it invalidates a mikvah in any volume; an earthenware spout invalidates a mikvah in the volume of a quarter-log. Rabbi Yosi says that an earthenware spout also invalidates in any volume; a quarter-log was only mentioned regarding the broken shards of an earthen vessel. If the gravel moves around inside the cavity, it invalidates a mikvah. If dirt goes down into it and gets compacted, the mikvah remains valid. If the spout is narrow at the ends and wide in the middle, it doesn’t invalidate a mikvah because it wasn’t made to serve as a receptacle.

Mikvaos 4:4

Let’s say that drawn water and rainwater mixed together in a courtyard, in a ditch or on the steps of a cave (containing a mikvah so that it flows down into the mikvah). If the major part of the mikvah was valid (i.e., rainwater), then the whole thing is valid; if the major part is invalid (i.e., drawn water), then the whole thing is invalid. If the two types of water were equal in volume, then the whole thing is invalid. This applies when the two types of water mix before reaching the mikvah; what if they flowed into the mikvah water? In that case, it was known that 40 seah of fit water fell in before three log of drawn water, the mikvah is valid; if this is not the case, then the mikvah is invalid.