The water must be blessed by a priest. In my opinion, there is no such thing as 'holy water'. The blessing of water, or anything else, by a 'priest' is mere superstition. 'Holiness' means the setting...
The simplest answer is that is is blessed by a priest.
A slightly more complex answer is that the Holy Spirit is channeled through the priest to make the water holy.
Answer.
You will probably get a...
Holy water is not a symbol of the holy trinity. The holy trinity has to do with the idea of Father, Son, and Holy Spirit. Holy water is used to show the "washing away" of sin.