510. Four Requirements for Hand Washing

Brachos 6:5

If a person has to wash his hands and he immerses them in a mikvah, that is sufficient. If he immerses them in a body of water that does not have the volume of a mikvah, or in water that was poured on the ground, he has accomplished nothing. Poured water is only effective when poured over the hands.

Brachos 6:6

One who washes his hands must ensure four things: (1) that the water used is suitable for washing hands; (2) that there is a volume of at least a revi’is (a little over three ounces) for both hands; (3) that he washes from a vessel; and (4) that the water is poured through human agency.