From a reader:
I am wondering what the rule is concerning mixing both wine and water for chalices that will be used for communion under both species. I have seen some priests only add the water to their own chalice, and other priests who add a drop of water to each individual chalice to be used for communion. Is there a certain way to do this?
Since I pretty much never am involved with concelebration with multiple chalices, I need to open the floor up to priests who do this sort of thing more often. On the rare occasion when I have been, I have this to attending deacons, etc.
That said, I think the GIRM only requires that the main chalice (singular), i.e., of the celebrant, must receive a small portion of water in the wine. Nothing is said about other chalices one way or another.
It strikes me as appropriate for water to be added to all the chalices at the time of the preparation of the celebrant’s chalice, but I don’t think that is prescribed.
Also, we must not after the consecration pour the Precious Blood from a container into chalices. Chalices should be prepared ahead of time (cf. Redemptionis Sacramentum).