Holding a full reviit of water in the washing cup at once

Hi,

We have said that one must use a reviit (just under four ounces) of water when washing his hands for bread.

Although one may divide up the reviit between the two pourings, an entire reviit must be held in the cup at the start. Thus one may not use a cup holding 2 ounces for the first pour, and then add 2 ounces for the second pour.

(Shulchan Aruch Orach Chaim 160:14; Mishneh Berurah 160:81)

Have a great day,
Mordechai