How much water must one pour each time?<a href="#_ftn1" name="_ftnref1">[1]</a> 
The above obligation is only regarding how much water must initially be in the vessel before beginning the pouring. Regarding the amount of water one must pour each time on his hand, there is no minimum measurement of a Revius. [However one must pour the amount of water needed to wash ones entire hand, up until his wrist, by each pouring.<a href="#_ftn2" name="_ftnref2">[2]</a>]
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<a href="#_ftnref1" name="_ftn1">[1]</a> 160:16 regarding washing for bread
<a href="#_ftnref2" name="_ftn2">[2]</a> Siddur; See Halacha C!

Shulchan Aruch HaRav | 📄 How much water must one pour each time by the morning washing

How much water must one pour each time?[1] The above obligation is only regarding how much water must initially be in the vessel before beginning the pouring. Regarding the amount of water one must pour each time on his hand, there is no minimum measurement of a Revius.