Yadayim, Chapter One, Mishnah Five
1) Water in which the baker dips his loaves is invalid;
a) But if he moistened his hands in the water it is valid.
2) All are fit to pour water over the hands, even a deaf-mute, an imbecile, or a minor.
3) A person may place the jug between his knees and pour out the water
a) Or he may turn the jug on its side and pour it out.
4) A monkey may pour water over the hands.
5) Rabbi Yose declares these [latter] two cases invalid.
Section one: If the baker dipped his loaves into the water, the water is invalid. This is the same as the rule in yesterday’s mishnah. Today’s mishnah adds that if the baker just uses the water to moisten his hands, and then from his hands he puts the water onto the loaves, the water remains valid because he didn’t put the loaves directly into the water.
Section two: After having discussed rules concerning the vessel and the water the mishnah now turns its attention to the person or power that pours the water over the hands. As we shall see, the requirement is that some power should cause the water to be poured over the hands. Water which flows on its own, for instance rainwater coming out of a drainage pipe, cannot be used for netilat yadayim.
There is no requirement for intention (kavvanah) for netilat yadayim. Therefore, even people who legally are not considered to have kavanah can pour the water.
Section three: A person puts a jug with water in it between his legs and then tilts it to the side. This is a valid way of performing netilat yadayim because his legs count as having caused the water to be poured onto his hands.
He can even tilt the jug on its side and then put his hands under the water pouring out. Even though the water is currently (no pun intended) coming out of the jug on its own, since he tilted the jug on its side, it counts as an outside power.
Section four: Even a monkey could pour water over someone’s hands. In other words, there must be an outside power, but that power need not be human.
Section five: Rabbi Yose says that the final two cases are invalid because the water needs to be poured by a force initiated by a person. So if the water flows from the barrel on its own or a monkey pours the water, the hand-washing is invalid.