Midrash su Levitico 15:11

3) "it shall be scoured and rinsed": I might think that just as "rinsing" elsewhere (Vayikra 15:11) is in forty sa'ah; here, too, it is in forty sa'ah; it is, therefore, written "with water" — any amount; "with water" — and not with wine; "with water" — and not with a dilution (of wine and water); "with water" — all water (and not just "living waters"); and it follows a fortiori that kiyor (laver) water (may be used).

5) (Vayikra 15:11) ("And whoever the zav touches, if he (the zav) did not wash his hands with water (i.e., if he did not immerse), shall wash his clothes and bathe in water, and he shall be unclean until the evening." (touches) "him": him and not the excrement upon him, and not the hair-knot upon it, and not the clasps, and not the nose rings, and not the finger rings, even though they do not come off. I might think to exclude the hair and the nails; it is, therefore, written "and he shall be unclean." "if he did not wash his hands with water": What is the intent of this? Because it is written "and he shall wash his flesh with water," I might think even the hidden parts; it is, therefore written "his hands." Just as his hands are visible, so all that is visible (is to be bathed), excluding the hidden parts.

6) "a plague-spot of leprosy and he shall see it": What is the intent of this? From (Vayikra 15:11) "And the Cohein shall declare him tamei; he shall not quarantine him" we learn that a confirmed leper is not to be quarantined.