EWTN Catholic Q&A
Blessing ourselves with Holy Water
Question from MM on 10-12-2013:

Why do we use the right hand to bless ourselves with Holy Water? Why can't we use the left hand?

Answer by Richard Geraghty on 10-16-2013:

Dear MM,

Although not everybody is right handed, the traditional way tp bless yourself is with the right hand, as you know. Such a practice reinforces the sense that we are part of a community that is the Church. Now it is the duty of the Church to teach us how to approach God. Blessing with the left hand does not give that message. Catholics are people of tradition. But our age rebels against tradition. So stick with the right hand.Its a gesture of Catholic solidarity.

Dr. Geraghty