CCC 1238
Christian Mystery›SECTION TWO THE SEVEN SACRAMENTS OF THE CHURCH›CHAPTER ONE THE SACRAMENTS OF CHRISTIAN INITIATION›III. How is the Sacrament of Baptism Celebrated?
The baptismal water is consecrated by a prayer of epiclesis (either at this moment or at the Easter Vigil). the Church asks God that through his Son the power of the Holy Spirit may be sent upon the water, so that those who will be baptized in it may be "born of water and the Spirit."