1) One should wash one’s hands in such a way that the water will reach the joint between one’s forearm and the palm of one’s hand. Others say that it is enough if the water reaches the joint between the fingers and the palm of the hand. It is correct to follow the first opinion. In case of necessity, for example if one does not have enough water, one may conduct oneself according to the latter opinion. (Shulchan Aruch and Mishne Berura 161)
2) If one’s hands were dirtied with sweat or something similar, everyone agrees that one must wash the hand right down to where it joins that forearm. (ibid)
