Catholic Catechism:
1278 The essential rite of Baptism consists in immersing the
candidate in water or pouring
water on his head, while pronouncing
the invocation of the Most Holy
Trinity: the Father, the Son, and
the Holy Spirit.
1219 The Church has seen in Noah's ark a prefiguring of salvation
by Baptism, for by it "a few,
that is, eight persons, were saved
through water": “The waters
of the great flood you made a sign of
the waters of Baptism, that make
an end of sin and a new
beginning of goodness.”
Council of Trent’s teaching:
Canon
II If any one says, that true and natural
water is not of necessity for baptism, and, on that
account, wrests,
to some sort of metaphor, those words of our Lord Jesus
Christ;
Unless a man be born again of water and the Holy Ghost;
let him
be anathema.