Hi Guys i sharing a extract from a book(Signs of Life) by Scott Hann, He wonderfully explains what is purpose of Holy water. which i dint know all these years,may be this gives you some insight.
Holy Water
We begin in water.
That’s how the book of Genesis poetically depicts the creation of the universe:
“darkness was upon the face of the deep; and the Spirit of God was moving over the face of the waters . . . And God said, ‘Let there be a firmament in the midst of the waters, and let it separate the waters from the waters’ ” (Gen 1:2, 6).
As it was in the cosmic, so it is in our personal beginnings: we assume our human form in the amniotic sac, “bag of waters,” in the womb. In the order of nature, birth begins when a mother’s “water breaks.”
So with water we begin our visits to church. We dip a hand into a holy-water font, and we bless ourselves.
There has been a watermark on Christian prayer since the earliest days of the Church. At the end of the second century, a North African theologian named Tertullian mentions the custom of symbolically cleansing one’s hands before lifting them in prayer. It was a Jewish custom that predated the coming of Our Lord, and it may be what St. Paul was referring to when he wrote to Timothy: “I desire then that in every place the men should pray, lifting holy hands” or “pure hands” (1 Tim 2:8). The historian Eusebius, writing around a.d. 320, describes a church in Tyre that had flowing fountains at its entrance, where the faithful might purify their hands.
We use water to mark our beginnings because God does. We find ample evidence of this in both nature and Scripture. When the world was lost to sin and needed cleansing and rebirth, God sent a great flood, and from that flood the family of Noah found newlife. When Israel emerged from slavery as a unified nation, it first had to pass through the waters of the Red Sea. When the chosen people established their places of worship—first the tabernacle and then the Temple—they constructed them with bronze basins for washing upon entry.
St. Thomas Aquinas taught that water has been a natural sacrament since the dawn of creation. In the age of nature—from Adam through the patriarchs—water refreshed and cleansed humankind. In the age of Law—the time of Moses—water provided a spiritual rebirth for Israel as the nation began its journey to the promised land. With Jesus, however, came the age of grace; and from that time onward water received the divine power of the Word made flesh. Though babies had always been born through “water,” now grown men and women could be “born of water and the Holy Spirit” (Jn 3:5). The Church Fathers taught that Jesus, by descending into the waters of the River Jordan, had sanctified the waters of the world. He made them living and life-giving (see Jn 4:10–14). He made them a source of supernatural regeneration, refreshment, and cleansing.
While we are on earth, we know spiritual things by means of sensible signs. It is only in glory that we will see divine things as they are, without their sacramental veils. According to St. Thomas, water ultimately “signifies the grace of the Holy Spirit . . . For the Holy Spirit is the unfailing fountain from whom all gifts of grace flow.” The book of Revelation confirms this, as it presents the Spirit’s grace as a “river of the water of life, bright as crystal, flowing from the throne of God and of the Lamb” (Rev 22:1).
Through history and through the cosmos, God has spoken with a voice that is “like the sound of many waters” (Rev 1:15). All the many sacred meanings of water we take for our own and claim as our inheritance—whenever we bless ourselves with holy water.
“Beloved, we are God’s children now,” born of water and the Spirit. “And everyone who thus hopes in him purifies himself as he is pure” (1 Jn 3:2-3).
This simple action, which even the smallest children love to do, is a reminder and a renewal of our baptism. It is a refreshment, too, providing relief from the oppression of evil. St. Teresa of Avila wrote that “there is nothing the devils flee from more—without returning—than holy water.”
Holy water is ordinary water that has been blessed for devotional use by a priest. We bless ourselves with holy water at church. Most churches also provide a dispenser so that parishioners can draw water to take home with them. Some Catholic families keep a little holy-water font at the entryway to every bedroom. I keep a bottle of the stuff in my office at all times.
We need do no more with it than splash a few drops on ourselves. It is customary to pronounce a blessing in the name of the Holy Trinity, too, and trace the outline of a cross with our right hand.
That’s enough for now. We’ll save the rest for the next chapter.
Ponder in Your Heart
King and Lord of all things and maker of the world: you gave salvation freely to all created nature by the descent of your only-begotten Jesus Christ. You redeemed all that you created by the coming of your ineffable Word. See now from heaven, and look upon these waters, and fill them with the Holy Spirit. Let your ineffable Word come to be in them and tranform their energy and cause them to be generative, as being filled with your grace . . . As your only-begotten Word coming down upon the waters of the Jordan rendered them holy, so now may he descend on these and make them holy and spiritual.
—Blessing of Water, from the sacramentary of
St. Serapion of Egypt, fourth century