Mikvaos, Chapter 4, Mishnah 2. This chapter is devoted to mayim she'uvim, drawn water. A mikveh that has not yet gathered its forty se'ah of rainwater is spoiled by the entry of three lugin of drawn water, and water earns that status when it has been received inside a keli, a vessel possessing a beis kibul, a hollow area meant to hold liquid or other contents. Our mishnah refines that definition further.
A Board with a Rim
"Hamani'ach tavla tachas hatzinor," one who sets a board beneath the drainpipe. A flat board placed under a spout serves to divert the runoff, steering it away from where it would otherwise land and sending it elsewhere. The question is whether the water that passes over such a board has been "received" in a vessel.
The mishnah answers: "im yesh lah gizveiz," if the board has a raised rim, meaning a rim running along all four of its sides, so that one face of the board is flat while the other is bounded on every side and thus forms a genuine receptacle, then "poselas es hamikveh." Water that lands on that board while it lies flat with the rimmed face upward becomes she'uvim and will disqualify a mikveh.
"Ve'im lav," and if it does not have a rim on all four sides but only on three, the ruling is "einah poselas es hamikveh." The water falling on it never becomes drawn water. Even though there is an enclosed hollow on three sides, that is not a beis kibul for these purposes.
Standing the Board Upright
"Zakfah lehadi'ach." Suppose the board does have its rim, but he did not lay it under the spout with the rim facing upward; instead he propped it up vertically. No water can now pool on it, and in any case it is not resting in the position it would occupy were it meant to gather water. Therefore "bein kach u'vein kach," whether or not the board is rimmed, "einah poselas es hamikveh." Since the board is not positioned derech kabbalah, in the manner of receiving, water passing over it never collects there as she'uvim.
A Summary: Six Conditions for She'uvim
Having reached this point, it is worth setting out in an orderly way what the poskim identify as the six conditions that must be met before water received in a vessel takes on the status of mayim she'uvim.
- One: the vessel has to be intact. Should there be a perforation in its base that lets the liquid run out, it does not qualify, a point taken up later in this chapter.
- Two: the keli requires a beis kibul closed off on all four sides, a border able to hold water around its entire perimeter. Enclosure on only three sides falls short.
- Three: that hollow space must have been formed with the purpose of holding liquid or other contents. Further on we meet objects that were not na'asu lekabbalah, never fashioned for holding anything, despite having a cavity in them.
- Four: the lesson of our mishnah, that the utensil be situated so that it can receive. A rimmed board must sit flat side down and rim side up, in a stance where collecting is actually possible.
- Five: the keli may not be joined to the earth. The case in view is one designed from the outset to be set into the ground, or one that was affixed first and hollowed out only afterward. Whatever gathers in such a cavity does not count as she'uvim.
- Six: as came up in earlier teachings and again here, the filling has to be lada'as, done knowingly. Water that accumulated in a utensil he had left somewhere and forgotten, with no plan for it to fill at all, is not drawn water.