Ex. 29:4; Lev. 8:6 - Aaron and his sons were washed in holy water in their consecration to the priesthood. Thus, we see the use of holy water during the beginning of salvation history.
Ex. 30:18-19 - the Lord requires Aaron and his sons to wash their hands and feet in holy water before they offered sacrifices to Him. The Church uses holy water for various purposes, and holy water fonts are generally located at the entrance of Catholic churches to be used before the sacrifice of Christ is offered to the Father.
Num. 5:17 - here again, the priest uses holy water. God uses natural matter to convey the supernatural, just as God who is Spirit became flesh in Christ Jesus.
Num. 8:7 - the Lord says to “sprinkle them with the water of remission.” The Lord uses water, a physical property, to convey His supernatural property of grace.
1 Kings 7:38-39 - in King Solomon’s temple, there were ten large basins of holy water. Holy water has always been used in the context of worship.
John 9:6-7 – Jesus uses clay and spittle to heal the blind man’s eyes, and ordered him to wash in the pool of Siloam to effect the cure. Jesus did not need to use spittle, clay and water, but He does to demonstrate that God uses the material things He created to give graces and heal us.
John 13:4-10 - the Lord uses water to wash the apostles’ feet to prepare them for their sacramental priesthood.
John 19:34 - water and blood flowed from Jesus’ pierced side on the Cross. The Church uses holy water as a symbol of our Lord’s life giving water that flowed from His sacred Heart, and as the property which brings about the power of Jesus Christ Himself, in baptism, the Eucharist, and other sacred rites of the Church.
This was all copied from Scripturecatholic.com, so it’s not mine