Why do we mix the wine with water in the chalice?

The answer

When the Lord was pierced in His side, blood and water came out. St. Augustine believes that mixing the Eucharistic blood with water indicates that water is a symbol of humanity which partakes in Christ’s suffering.

Fr. Tadros Yacoub Malaty

Fr. Tadros Yacoub Malaty, Catechism of the Coptic Orthodox Church, Volume 1, Books 1–3. First English Edition, 2023. Published by St. George Coptic Orthodox Church, Sporting, Alexandria, and Queen St. Mary & Prince Tadros Coptic Orthodox Church, South Brunswick, NJ. Copyright © 2023. Translation and Editing: Youth of the Coptic Orthodox Church in the USA, Canada, Europe, Australia, Arabian Gulf, and Egypt.