I am wondering how one fills a mikve for the first time?

Most of the works I consulted on the topic (e.g., the very good document here or Artscroll Mishna Mikvaos) mention "forty seah of rainwater are gathered into a bor" but without details on how to accomplish this practically. Remember that for a kosher mikve, water has to flow naturally and cannot be drawn from containers.

I know it is possible to fill a mikve with ice (under very strict conditions) but assume that ice is not available everywhere, especially in summer months. And since I have seen opinions ranging from 575-1000 liters for forty seah, I assume waiting for rainfall to occur naturally during construction might take a long time, and not work at all for months in hot regions (e.g., Israel).

So what is practically being done?

  • 1
    What's wrong with construction taking a few months? This isn't something you order on Amazon Prime
    – Double AA
    Jun 3, 2020 at 12:25
  • @DoubleAA I can see at least two things going wrong: (1) if you leave water stagnate over months, it will turn bad and (2) still after months you might not get the quantity you need. Anyway I am asking a fact-based question, either people know what is practiced or not. Maybe mikve constructors are waiting months but I would guess not. I am continuing to research this and will post back what I learn
    – mbloch
    Jun 3, 2020 at 12:27
  • They must have a way of keeping the water from going bad even after they build it.
    – Double AA
    Jun 3, 2020 at 14:41
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    @DoubleAA could be - chemicals (e.g., chlorine) could do this like in a pool - question is whether they remove the status of rainwater (e.g., if accumulation over the months is > 3 luggin). The other alternative appears to feed it from a spring
    – mbloch
    Jun 3, 2020 at 14:43

1 Answer 1


One source of water would be an artesian aquifer.

(For an example of using artesian water for a mikveh see here.) Ideally the water would just flow into the mikveh. If it's not possible, there are ways of bringing the water up from the artesian well without making it become "shauvin" "drawn" water which would be invalid. I remember learning that this is done for mikvaos by using air pressure. (I'll try and source this last claim.)

It's also worth noting that there is a major machlokes regarding using artificial ice for a mikveh. It's a "hot topic" with major opinions on both sides, but there are halachically valid opinions who would allow for creating ice in a machine from tap water and using that for creating a mikveh.

When I learned mikvaos a number of rabbonim told me that we only rely on this b'shas dechak gadol, until some other kosher water could be obtained; but CYLOR.

See this article for background info about using natural or artificial ice.

  • 1
    I see now that page 71 here describes an air pressure system similar to what you describe
    – mbloch
    Jun 3, 2020 at 12:35

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