Yisrael 2:29 and Halikhot Shlomo 2:5).
The essential objective of netilat yadayim before Shaĥarit is cleanliness, as it is written (Tehilim 26:6): “I wash my hands clean,” and as detailed in Berakhot 15a. The reason for washing one’s hands before a meal is purification and sanctification, similar to the washing of the kohanim’s hands in the kiyor (laver) before serving in the Temple. Although there is a difference between the objectives of the two washings, the Sages instituted the morning netilat yadayim based on the model of washing before a meal, and even the berakha has the same wording. Le-khatĥila, when washing in the morning, one should take care that all the necessary requirements for washing one’s hands before a meal are met – that there is at least a revi’it of water, that she washes with a vessel, that there is human force involved in the pouring (ko’aĥ gavra), and that the appearance of the water has not changed. Be-di’avad, even if there is no revi’it of water there, or a vessel, or human force, since the water does in fact clean one for prayer, it is the opinion of SA and Rema that Al Netilat Yadayim is recited. If the appearance of the water has changed and has become unacceptable for washing before a meal, one may use it to wash her hands for Shaĥarit, but instead recite “al nekiyut yadayim” (SA 4:1, 6, 7, and 22). However, MB, 4:7, and BHL state that according to many Aĥaronim, even if the water becomes invalid for washing before a meal, one may recite Al Netilat Yadayim when washing before Shaĥarit because the water does clean her hands enough for prayer. Kaf Ha-ĥayim 4:11 and Halakha Berura 4:12 state that one does not recite a berakha on the morning netilat yadayim if there is anything that renders it invalid for washing before a meal. ]