1) The amount of water for washing one’s hand is a Revi’is. According to the letter of the Law, one may use one Revi’is for both hands, but in this case there are many different laws which not everyone knows, and therefore ideally one should use a full Revi’is for each hand. (Mishne Berura 158)
2)It is appropriate to use more than this measurement and to wash with an abundance of water, as one of the Amoraim said, that he washed his hands with handfuls of water and received in return handfuls of goodness. However, one must do this for the honor of Hashem and not just in order to receive a reward, and the reward will come by itself. (ibid)
