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If I have a mikva which needs filling, and there is no rain, can I use the following mechanism -

I have a Mikva in a closed room. On top of this Mikva, there is a cooling system (let's say that this cooling system isn't a kli [it's recessed into the roof]). Close to this Mikva there is a pot of water on a stove. The water boils, evaporates, condenses on the cooler and then falls into the Mikva.

There is an argument whether frozen Mayim Sheuvin (drawn water) that melts are considered enough of a "panim chadashos" (lit. new face. Means here that the original thing changed form enough to be considered a totally new thing) as to loose their original status of "Mayim Sheuvin", as perhaps one can say that "ice" is water just in a frozen state (and thus frozen mayim sheuvin are pasul). However, there seems to be no panim chadashos greater than re-condensed boiled water?

If this system doesn't work (if it's not "panim chadashos" enough), what about having the cooler condense natural water vapor? At first glance, there should be no chashash since there is no mayim sheuvin involved anywhere?

Do Poskim discuss this question? Please bring sources.


What about evaporated Mei Peiros (fruit juice)? Do we say that just like (if) evaporated mayim sheuvim changes to "mei geshamim", evaporated Mei Peiros change to "mei geshamim" or do we say that it stays "mei peiros" (lo maalin velo mordin)?

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I can't imagine anything wrong with the second system. (Nor really with the first system, but I say that with less certainty.) – Double AA Mar 7 '13 at 23:25
This can be a very important question for the future when mikvahs are needed on spaceships or on other planets. – user2636 Apr 8 '13 at 4:24
@BubbaMetzia Even this wouldn't help you on a spaceship as a mikva cannot be in a vessel but must be in the ground. – Double AA Apr 8 '13 at 4:40
@ShmuelBrin I don't know, but at least we know he's not fleishig! – Double AA Apr 8 '13 at 5:06
R' Menashe Klein discusses the issue here: hebrewbooks.org/pdfpager.aspx?req=1874&st=&pgnum=3 – Ephraim Mar 4 '14 at 20:02
up vote 6 down vote accepted

As Ephraim already mentioned, HaRav Menashe Klein discusses this in משנה הלכות חלק ב.

He brings a Chazon Ish in חידושי חזו"א מקואות תנינא סי' יו"ד ס"ק י"א which talks about using condensed steam for a Mikva.

The Chazon Ish says it should have the same status as melted ice and it definitely doesn't make the Mikve Pasul, even if the condensation dripped in before the 40 Kosher Seah.

However, he does not allow one to use the steam instead of Kosher Mikveh-water, as we never do anything regarding a Mikva that we didn't hear from our teachers.

That said, the Chazon Ish says that condensation cannot be worse than המשכה and therefore a Mikve would be Kosher if less than 50% of the original 40 Kosher-Seah consisted of condensation.

Rav Menashe Klein is less sure about this, as we have a Mishna in מכשירין פ"ה מ"י and other places where it seems that steam retains the Tum'a status of the water it came from. However, he (reluctantly?) allows one to melt the ice using steam, which was the original question he addressed.

This is opposed to ice; water loses its Tum'a once frozen.

As to steamed fruit juice, he seems to prove it has the same status as water.

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