The Shulchan Aruch says that if a bit of milk falls into a pot of meat, if that piece of milk is less than the meat it's Botul Bushishim. Why do we say by Mikvah that if you've got 40 Seoh of water Kosher for a Mikvah, no matter how much Mayim Shuvim falls in it's Botul as the water falls in. How come by Mikvah we say water is Botul no matter how much water falls in, it's Botul as it falls in, and by Bossor Vocholov the bits of milk add up and are then Botul?
Aaron Pacanowski, Melbourne, Australia
Dear Aaron,
I understood your question as follows: Why by the pot of meat will it eventually be forbidden if more and more milk falls in, but additional Mayim She'uvim will never ruin a proper Mikvah?
Answer: we can ignore small amounts of milk, but the milk which remains when joined by more milk cannot be ignored.
Mayim She'uvim, after entering the Kosher Mikvah, loses its Isur. All the water is now Mikvah water. The Rosh (end of Nidah, Hilchos Mikva'os 1), after bringing many proofs, adds that this is true by Sevara (logic) - even Tamei water becomes Tahor when coming in contact with Mikvah water (Beitzah 17b) (what is known as Hashakah).
All the best,
Reuven Weiner