The earliest Christian work I’ve come across to make reference to this question is the Odes of Solomon. Dated by the translator to the, “Late First to Early Second Century A.D.,” it comes from, “a collection of very early Christian hymns.” Regarding the provenance, it is noted that, “If the Odes were composed around A.D. 100 in Syriac, are from the same community or region in which the Gospel of John was composed, and were familiar to Ignatius or contained the same Christian tone and ideas as those found in his letters, then the most probable provenance is Antioch or somewhere near that city.” And relevant to the question at hand is the significance that, “the Odes are a window through which we can occasionally glimpse the earliest Christians at worship”1:
“For from the Most High the drink was given.
“Blessed, therefore, are the ministers of that drink, who have been entrusted with his water.”2
One scholarly commentator noted the following on these verses:
“The fact that the Eucharist was also celebrated with water shows that the early Christians were mainly interested in the symbolism of the mysteries and not in the literal observance of the sacrament.”3
Verse 18 went on to refer to those who received this water: “Everyone recognized them as the Lord’s, and lived by the living water of eternity,” the footnote to which refers us to the following passage from Ignatius of Antioch: “there is in me a Living Water, which is eloquent and within me says: ‘Come to the Father.’ I have no taste for corruptible food or for the delights of this life. Bread of God is what I desire; that is the Flesh of Jesus Christ, who was of the seed of David; and for my drink I desire His Blood, that is, incorruptible love”4. Note the Eucharistic reference to water, which alludes to John 4:10, and to bread, which alludes to John 6:33.
The next source in chronological order comes from Justin Martyr in the middle of the second century, writing from Rome, and at first glance seems to offer a different tradition:
“Then there is brought to the president of the brothers bread and a cup of wine mixed with water,”5 etc.
The commentary from the translators, however, reveals that the exact meaning here is not so straight forward as one might initially suppose and is debated by patristic scholars. Said commentary also provides us with a summation on the position on the matter as taken by Irenaeus and Hippolytus:
“The MS has ‘a cup of water and mixture’. The phrase has worried editors and translators, since the word κράμα itself means ‘wine mixed with water’. Various solutions have been proposed; e.g. that the text originally spoke only of a cup of mixed wine ([Charles] Ashton) or only of a cup of water ([Adolf von] Harnack—in support of whom cf. D[ialogue With Trypho] 70:4), or of a cup of water and a cup of mixed wine ([Miroslav] Marcovich, [Leslie William] Barnard, etc.). The [Treatise on the] Apostolic Tradition [by Hippolytus] (Dix, 23) records the offering of a cup of water as well as cups of wine mixed with water, and of milk mingled with honey, in the post-baptismal mass. . . . A further reason behind Justin’s stress on the use of water could lie in the fact that that usage had theological significance for him, as it clearly would for Irenaeus a generation later. Irenaeus does not develop that significance, but it is implicit in his denunciation of the water-only eucharist of the Ebionites (A[gainst ]H[eresies] V.1.3). There wine represents the presence of the Spirit, and water corresponds to the ‘ancient formation of humankind’ (antiquam formationem hominis). Now, it would be a big jump to retroject that symbolism into Justin, but it is far from impossible that it is there. . . . These suggestions are, however, admittedly speculative, and the darkness enveloping mid-2nd-century practice is too thick for us to feel confidence in them. Accordingly, while we regard this reconstruction as not implausible, we have made the palaeographically simple emendation to ‘a cup mixed with water’, and have expanded this in the translation to indicate that the water was mixed with wine.”6
The source by Hippolytus referenced above warrants further investigation:
“And then let the oblation be brought at once by the deacons to the bishop, and let him give thanks over the bread as the antitype of the body of Christ; and the cup mixed with wine on account of the likeness of the blood which was shed for all who have put their faith in him. . . . And water is offered as a sign of the washing, so that the inner person, which is made up of the soul, should receive the same as the body.”7
On which we are given this scholarly commentary from the translator which corresponds to the above:
“Water was frequently used in eucharistic meals in the ancient church; most relevant as a parallel however is the use of a cup of water in the baptismal Eucharist described by Justin First Apology 65; the question of whether wine was also used on this occasion is controversial.”8