If one does not have enough water to wash his hands three times properly, then he should wash [each hand one time pouring a Revius on each hand, or if he only has one Revius of water then he should wash] both hands simultaneously, pouring the Revius of water over them. One then says the blessing of Al Netilas Yadayim. [If one does not even have a Revius of water available then he may not wash with less than a Revius and recite a blessing. In all cases one is to rewash his hands properly when water becomes available. See Halacha 15 regarding if there is no water available at all.]
Do the restrictions that apply prior to morning washing still apply after this single washing?
One is not to nullify himself from learning Torah or saying blessings until he finds enough water to wash three times on each hand. One may even be lenient to permit touching clothing or walking four Amos after this washing. However one is to be stringent to avoid touching the orifices of the body, and certainly food, until he is able to wash properly each hand three times. The above leniencies apply even if one did not have a Revius worth of water to wash his hands.
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 Siddur Seder Netila; Not mentioned in Basra; So rules also Rav Akiva Eiger brought in Kaf Hachaim 4/104
Ruling of Admur in Kama: In Kama 4/3 Admur rules that one may wash with a blessing of Al Netilas Yadayim even if less than a Revius of water is available.
 The reason one is able to recite the blessing: Although the impure spirit only completely leaves if one washes each hand three times, nevertheless [completely] removing the impurity is not the only reason behind the institution of the washing, as one also needs to wash in order to sanctify himself with the holiness of G-d and remove the impurity from his hands like a Kohen which sanctifies his hands from the Kiyur. Now since for a Kohen washing one time suffices, in this case as well he can wash one time and say a blessing. [Siddur] From the wording here it is proven that although the impurity is only completely removed with three pourings, nevertheless even one pouring removes some of the impurity, and thus by washing one time one has sanctified himself before G-d to the best of his ability. [Ketzos Hashulchan 2 footnote 11]
Reason of Kama: According to the Kama 4/1 the impurity on ones hands has nothing to do with the reason of sanctification like a Kohen. [See Halacha 2] Thus even if no impurity is removed from the hands one may recite a blessing.
 Siddur based on that all the laws that apply by washing for a meal apply likewise for the morning washing. See Halacha 7H. Furthermore without a Revius the impurity is not removed even slightly.
Ruling of Admur in Kama: In Kama 4/3 Admur rules: “If one does not have a Revius of water available he may nevertheless wash with a blessing being that the Sages did not differentiate [in the amount of water] as one is nevertheless washing with valid water.” The reason why a blessing may be said is because according to the Kama 4/1 the impurity on ones hands has nothing to do with the reason of sanctification like a Kohen. [See Halacha 2] Thus even if no impurity is removed from the hands one may recite a blessing.
 This is done in order to completely remove the impurity from one’s hand, as rules Admur regarding one who dips his hands in a Mikvah. [See Halacha 13C]
 Ketzos Hashulchan 2/3 footnote 11 based on Siddur; Ateres Zikeinim 4/3: “After slightly washing one’s hands he may walk four Amos and touch clothing.”
This ruling of the Ketzos Hashulchan is based on Siddur Hilchos Netilas Yadayim. Although in the Siddur this was said regarding a case that one only “washed a little, or cleaned his hands without water” and not if one poured a Revius on one hand, nevertheless it is logical to say that it applies likewise in this case, until one washes properly. [So learns Ketzos Hashulchan 2/3]
 See Chapter 3 Halacha 7A
 The reason to differentiate between the touching of orifices and food and the walking of four cubits and touching of clothing, is because the touching of orifices and food is warned against in the Talmud while the restriction of walking four Amos and touching clothing is only in accordance to the Zohar, and thus is more lenient. [Ketzos Hashulchan ibid; See Chapter 3 Halacha 7]
 Ketzos Hashulchan Supplement p. 82 based on Siddur; Ateres Zikeinim 4/3