Even though most women never become zavot [women who have seen blood after the first seven days], still I wonder why there is no mention of "מים חיים" [live waters-- or river or spring]in their case? I mean to say- that the law of the Torah is a nida [the regular monthly cycle] sits seven days and goes into a collection of water [a place where rain water has collected.] Still there is a custom to sit seven clean days.. Seven clean days is for a zava. So if you are worried about a zava (even if you are pretty sure she is not a zava) then why not require a spring or river? At least be consistent. If she is a zava? Fine. Have her wait seven clean days and send her to a spring or sea. If she is just a nida, then why wait seven days? Make up your mind.
