As early as the 5th century Holy Water has been used in the rites and ceremonies of the church, most notably in the sprinkling of the faithful as they enter the Church on Sunday.
Baptismal fonts were traditionally placed at the entrance of the Church, in the narthex so as the faithful passed by they would be reminded of their own baptism. Down through the centuries other traditions developed. Fonts were removed to the front of the Church or placed in the crossing.
The sprinkling of the faithful was kept for special Holy days and eventually, in our tradition, used on those Sundays designated for baptisms in the absence of candidates for the Sacrament.
Eventually holy water stoups,small containers for holy water, were placed near the entrance of the Church. The faithful would then dip their finger into the water and sign themselves with the cross to remind themselves of their baptismal promises.
Holy water is blessed by a priest or bishop. The formula is ancient and includes an exorcism of the water before it is blessed for religious purposes.Holy water is disposed of by pouring directly on the ground.