Holy water is water that has been blessed by a member of the clergy or a religious figure, or derived from a well or spring considered holy. The use for cleansing prior to a baptism and spiritual cleansing is common in several religions, from Christianity to Sikhism. The use of holy water as a sacramental for protection against evil is common among Lutherans, Anglicans, Roman Catholics, and Eastern Christians.
Water of lustration
In Catholicism, Lutheranism, Anglicanism, Eastern Orthodoxy, Oriental Orthodoxy and some other churches, holy water is water that has been sanctified by a priest for the purpose of baptism, for the blessing of persons, places, and objects, or as a means of repelling evil.
The Apostolic Constitutions, whose texts date to about the year 400 AD, attribute the precept of using holy water to the Apostle Matthew. It is plausible that the earliest Christians may have used water for expiatory and purificatory purposes in a way analogous to its employment in Jewish Law ("And he shall take holy water in an earthen vessel, and he shall cast a little earth of the pavement of the tabernacle into it", Numbers 5:17). Yet in many cases, the water used for the sacrament of Baptism was flowing water, sea- or river-water, which — in the view of the Catholic Church — could not receive the same blessing as that water contained in the baptisteries. However, Eastern Orthodox Christians do perform the same blessing, whether in a baptistery or for an outdoor body of water.
Sprinkling with holy water is used as a sacramental that recalls baptism. In the West the blessing of the water is traditionally accompanied by exorcism and by the addition of exorcised and blessed salt.
Holy water is kept in the holy water font, which is typically located at the entrance to the church (or sometimes in a separate room or building called a baptistery). Smaller vessels, called stoups, are usually placed at the entrances of the church, to enable people to bless themselves with it on entering.