The Rite of Baptism says, 
"All lay persons, since they belong to the priestly people, and especially parents and, by reason of their work, catechists, obstetricians, ... nurses of the sick, as well as physicians and surgeons, should know the proper method of baptizing in cases of necessity" (Rite of Baptism, 17).


In the case of necessity (e.g., the danger of death): 

***The person who baptizes pours water three times over the candidate's head, or immerses the candidate three times in water, while simultaneously pronouncing the baptismal formula: 

"(Name of child), I baptize you in the name of the Father (the minster pours water or immerses the first time),

and of the Son (the minister pours water or immerses a second time),

and of the Holy Spirit (the minister pours water or immerses a third time)."


A lay person who administers an emergency baptism must at least have the intention to do what the Church does when baptizing. It is also desirable that, as far as possible, one or two witnesses to the baptism be present.

When baptism has been administered neither by the pastor nor in his presence, the minister of the baptism, whoever that was, must inform the pastor of the parish in whose territory the baptism occured, so that the pastor may record it in accord with Canon 877, §1.