The celebration of Theophany, together with the blessing of waters is a uniquely Eastern Christian tradition. The Western Christian tradition celebrates the visitation of the Magi to the young Jesus. These two traditions are not at odds with one another, though. In our Christmas hymnography, we Orthodox sing of the wise men, who were taught by a star to adore Jesus, the Sun of Righteousness ["sun of righteousness" being a reference to Malachi 4:2]. Jesus is the light of the wisdom unto the world. Indeed, Jesus is the Wisdom of God [e.g. Proverbs 8:22 ff]. This is also what we see at Theophany, for being the Wisdom of God, he has always been present with and to God, and thus is fully God himself as well. At Theophany, the Father calls Jesus his “beloved Son,” as a way of describing their relationship to one another. This same Jesus, or Son of God, is also the “Light of the world” [see John 8:12]. Light, Wisdom, Son, all are applied to the one and same Lord Jesus, the Christ. At Theophany, this all comes together in a special way, and we encounter God the Father, the Son, and the Holy Spirit. This revelation of God, this Theophany, is also linked directly to the re-establishment of creation’s intended end–to radiate the divine goodness of God and serve as a vehicle for giving him thanks. At Theophany, we celebrate this with the blessing of waters. Through our prayers and the grace of the Holy Spirit, we ask God to make the water, and by extension, all that is blessed with it, holy water, done not so as to be a polar opposite of “secular water” (if you will) but as the fulfillment of what water is to be, what it was to be in Paradise and what it will be again in the Kingdom of Heaven.
Those interested in learning more about this blessing of waters and the history behind it should check this out: