שאו ידיכם קודש וברכו את ה'
The Kohanim must wash their hands before going up for Birkas Kohanim, as the posuk says (תהילים קל"ד, ב'), “שאו ידיכם קודש וברכו את ה'” (גמ' סוטה דף ל"ט ע"א, שו"ע ס"ו ).
Morning Netilas Yodayim
Some poskim hold a Kohen may rely on the netilas yodayim he did in the morning before davening, and he does not need to wash his hands again before Birkas Kohanim (הובא בתוס' סוטה שם ד"ה כל כהן, רמב"ם הובא בב"י).
Right before Birkas Kohanim. However, most Rishonim argue and hold the Kohanim must wash their hands again before Birkas Kohanim, because the Gemara says (ברכות דף מ"ב ע"א ), “Immediately after sanctifying comes the bracha” (רש"י ותוס' שם ). This is the psak (שו"ע ).
No water. If one does not have water, he may rely on the opinion that he is yotzei with the morning netilas yodayim if he washed his entire hands in the morning (שער הציון סקכ"ד ), as long as he did not lose focus [היסח הדעת ] and knows he did not touch an unclean area (מ"ב סק"כ ).
No other choice. In a very crowded shul, e.g., Yomim Nora’im at a Chassidishe Rebbe or the like, when it is very difficult for each Kohen to go outside to wash their hands due to the packed crowds, the Kohanim may rely on the above opinion that they can rely on their netilas yodayim before davening. They should be careful not to lose focus of their netilas yodayim until after Birkas Kohanim, and they should not touch unclean places, areas with sweat, or the like, as mentioned (מו"ר בעל שבט הקהתי).
Washed for Shacharis Birkas Kohanim. If a Kohen washed his hands for the Shacharis Birkas Kohanim, strictly speaking he does not need to wash again for the Mussaf Birkas Kohanim if he did not go outside or get distracted. However, the minhag is to wash again before the Mussaf Birkas Kohanim.
When to Wash
Before רצה. L’chatchila, the Kohanim should try to wash their hands before the bracha of רצה so that when רצה is being said, they are already prepared and ready to do Birkas Kohanim (מ"ב סקכ"ז ). Still, they should wash as close as possible to the beginning of רצה to prevent too long of a break between washing and the bracha. B’dieved, if a Kohen did not wash before רצה, he can wash after רצה too (מ"ב סקכ"ז ) as long as he began going up for Birkas Kohanim during רצה (מ"ב סקכ"ח ) and water for washing is brought to him near the front of the shul.
“Uprooting the Feet” to Wash the Hands
We mentioned (11) that to be obligated in Birkas Kohanim, a Kohen must begin going up during the shliach tzibbur’s tefilla of רצה. There is a machlokes haposkim regarding the halacha if a Kohen left his place during רצה to go out and wash his hands but did not get a chance to begin going up to the front after washing before the shliach tzibbur finished the bracha of Avoda, i.e., until he said “המחזיר שכינתו לציון.” Is it considered that the Kohen began going up during רצה?
No. Some rule that leaving one’s place to wash is not considered “uprooting the feet” to allow a Kohen to go up for Birkas Kohanim. Thus, if the shliach tzibbur already started רצה, the Kohen should rush out to wash his hands so that he will have time to start going up after washing before the shliach tzibbur finishes “המחזיר שכינתו לציון.” However, if he already finished the entire bracha of Avoda and a Kohen did not yet start going up to the front, he should not go up (מ'''ב סקכ"ח ); but if he did go up, he should stay (שער הציון שם ).
Yes. However, some are meikel and hold leaving one’s place to wash his hands is considered “uprooting the feet” since washing is a preparation for Birkas Kohanim (פמ"ג, ערוה"ש סט"ו ). B’dieved one can rely on this.
Type of Washing
The Kohen must wash with water. Wiping his hands on pebbles, dirt, or anything that can clean—which suffices for tefilla and Krias Shema b’dieved (שו"ע סי' צ"ב ס"ד )—does not suffice b’dieved, as this washing is like the Kohanim washing their hands for the avoda, for which wiping the hands certainly did not suffice (מ"ב סקי"ט ).
Entire hand. The Kohanim must wash their entire hands until the wrist, like when the Kohanim washed their hands for the avoda in the Beis HaMikdash (שו"ע ס"ו ).
No bracha. The poskim discuss whether a Kohen makes a bracha on washing his hands. In practice, the minhag is not to make a bracha even if a Kohen lost focus of his morning netilas yodayim before Shacharis.
Washing Through Leviim
The minhag is for a Levi to pour water over the Kohanim’s hands. The reason is to add kedusha through holy people. The Leviim are called holy, as the posuk (במדבר ח', י"ז ) says “וקדשת את הלויים” (הב"י בשם מדרש זוהר פ' נשא ). While this is not essential at all, Leviim should do this in all places.
Levi washing his own hands. The Sefardi minhag is that the Levi washes his own hands before washing the Kohanim’s hands (שו"ע ס"ו ); the Ashkenazi minhag is that the Levi does not wash his hands first (רמ"א שם ). However, if a Levi lost focus of his netilas yodayim before Shacharis or he touched an unclean area, it is proper for him to wash his hands before washing the Kohanim’s hands (מ"ב סקכ"ג ).
No Levi. If there is no Levi present, a bechor, i.e., firstborn of his mother, should wash the Kohanim’s hands, as bechoros also have some kedusha. If there is no bechor either, the Kohen should wash his own hands; he should not have a Yisroel wash his hands (מ"ב סקכ"ב ).
Levi talmid chacham, Kohen am haaretz. Some write that a Levi who is a talmid chacham, e.g., a big rav or rosh yeshiva, does not need to wash the hands of a Kohen who is an am haaretz even if there is no other Levi there. The reason is so as not to disrespect the honor of his Torah (כנה"ג הובא בבאה "ט סק"ח, בן איש חי תצוה ז').
However, most poskim hold that a Levi talmid chacham should not refrain from fulfilling the minhag that comes from the Zohar; on the contrary, this is his honor and his mitzva (מ"ב סקכ"ב, שו"ע הגר"ז סקי"א ). It is known that several world-class gedolim who were Leviim washed Kohanim’s hands (עי' תשוה "נ ח"ב קט שהגאב"ד בריסק נהג כן ברגל ). This was the practice of the Shevet HaLevi.
Multiple Leviim washing together. The common minhag is for multiple Leviim to wash a Kohen’s hands, i.e., multiple Leviim hold the cup and wash the Kohen’s hands all together. Some question this, as two people doing this is an abnormal form of washing (הגרי"ש אלישיב הובא בשבט הקהתי ח"ב סי' נ"ז ). However, a justification is that since they are doing this to give everyone a share out of love for the mitzva, it is considered a normal form of washing for this purpose (מו"ר בעל שבט הקהתי ).
