Here’s the text from the USCCB website
CDWDS Offers Guidance on the Mixture of Wine and Water at Mass
The Secretariat of Divine Worship frequently receives inquiries about the practice of mixing water and wine in
the chalice during the preparation of the gifts at Mass, specifically how this is to be carried out if there are
several chalices prepared when Holy Communion is distributed under both species. In a letter dated April 30,
2012 (Prot. n. 1193/11/L), Archbishop J. Augustine Di Noia, O.P., Secretary of the Congregation for Divine
Worship and the Discipline of the Sacraments, offered to Archbishop Gregory Aymond, Committee Chairman,
an observation regarding the practice, as the Congregation, too, has received questions about how to interpret
and enact the rubrics in this regard.
Archbishop Di Noia writes: “[T]his Congregation takes the view that it is sufficient for the water to be added
only to the chalice used by the main Celebrant. The addition of water to the other chalices, however, would not
in any way be considered to be an abuse.” Canon 924 §1 states, “The most holy Eucharistic sacrifice must be
offered with bread and with wine in which a little water must be mixed.” Still, it has long been held, and
affirmed by the Council of Trent, that the ritual mixing of wine and water is symbolic of the blood and water
flowing from Christ’s side as he hung upon the cross. The words spoken as the gesture is carried out, “By the
mystery of this water and wine may we come to share in the divinity of Christ who humbled himself to share in
our humanity,” also indicate that the mixing represents the unification of Christ’s divinity with our humanity
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