Why does it say "Shiv'as Yamim l'Taharaso"?
Rashi: To teach us that the Zav must count seven consecutive clean days, in that, should he see Zivus in the middle, he must begin counting seven clean days again from the beginning.
What is "Mayim Chayim"?
Rashi: "Mayim Chayim" means spring-water. 1
A Zav is the only Tamei person who needs to immerse in spring-water, and not in a regular Mikvah. (EC)
Which Chiyuv Misah is the Pasuk referring to?