to biblical law any collection of water, drawn or
otherwise, is suitable for a mikveh as long as it
contains enough for a person to immerse himself (Yad,
The rabbis, however, enacted that only water which had
not been drawn, i.e., has not been in a vessel or
receptacle, may be used; and they further established
that the minimum quantity for immersion is that which is
contained in a square cubit to the height of three
A mikveh containing less than this amount (which they
estimated to be a volume of 40 seah, between 250 1,000
liters according to various calculations) becomes invalid
should three log of water fall into it or be added.
However, if the mikveh contains more than this amount it
can never become invalid no matter how much drawn water
is added to it.
part 1 || part 2