When is one halachically required to wash one's hands, i.e. to Netilat Yadayim? Answer:
One is required to wash one's hands with a kli (cup) and say the bracha "al netilat yadayim" before reciting Shema, before all Tefillot (18 Brachot): Shacharit, Mincha, and Arvit (See Rambam's MT, Hilchot Tefillah 4:1-3 and Hilchot Brachot 6:1-2; Rosh Brachot 9:23; Shulhan Aruch OH 4:23 and Gra ad loc. 33 & 34; Maase Rav (Gra) 3). One is required to wash one's hands before Kriyat Shema as well when it is recited separately - see MT Hilchot Kriyat Shema 3:1.
Netilat Yadayim is also performed before eating bread or any food that was dipped in liquids such as wine, vinegar, honey, water, olive oil, or milk (Rambam, Hilchot Brachot 6:1-2; see too Kriyat Shema' 3:1, Tefillah 4:1-2).
Must I wash with a cup in the morning before saying birkot hashahar?
Answer No, the only parts of the tefillah which require washing with a cup before saying them are Kriyat Shema and Shmonei Esrei.
How much water is required for NY and how many times? Answer:
One revi'ith (80 ml = a little over 1 ⁄3 of a standard cup) must be poured simultaneously on both hands (Rambam, Hilchot Brachot 6:7) - this is the minimal requirement, but it is difficult to manage this unless another person pours. Practically, therefore, one revi'ith (once) must be poured on each hand. It is unnecessary and wasteful to use copious quantities of water.
Must one's hands be clean before NY? Answer:
Not necessarily. One aim of NY is cleansing the hands. If pouring water over them in the usual manner renders them clean, nothing more is required. If not - such as dirt that is not removed by water alone, or if an unpleasant odor emanates from one's hands - one should first wash them with soap (see Rambam, Hilchot Kriyat Shema 3:11) and then do NY. It is not necessary to dry one's hands in between (see next question).
Can one do NY with wet hands?
Yes, as long as one revi'ith (80 ml. = a little over 1 ⁄3 of a standard cup) is poured simultaneously on both hands (difficult) or if a revi'ith is poured on each hand.
Before I leave work to daven Mincha I first do netilat yadayim with a bracha. On my way to the shul I take a short-cut which involves me leaning with my hands on an outside concrete surface. Does touching that surface mean that the netilah which I did is not valid?
So long as any dust which goes on your hands is easily removable without the need to wash them then the netilah which was done is is still effective. One should simply wipe off whatever dust may be on one's hands and continue onward towards davening.
Just as with washing one's hands for eating bread, if one knows that no "heseh hada'ath" took place from the time one's hands were last washed, one is not required to wash again (see Rambam's MT. Brachot 6:18). Thus if one washed one's hands before Shacharit and did nothing that would require netilat yadayim such as going to the bathroom, there is no need to wash for Mussaf. The same applies when Arvit is recited on the heels of Mincha.
1st of Shevat, 5782 Sunday, 02 January 2022