Baptism doesn't save anyone; salvation is always a gift of God.The baptism that saves us is clearly stated by Jesus himself in Mt 16:16
"He who believes and is baptized will be saved"
The only baptism that anyone had experienced at this point was baptism with water.
Pater, after referring to 8 people being saved through water says "Baptism, which corresponds to this, now saves you"; a clear reference to baptism with water saving us.
Ephesians 2:8-9, "For by grace you are saved through faith, and this is not from yourselves, it is the gift of God; it is not from works, so that no one can boast."
In this case, the ritual of baptism is a work; it doesn't save anyone.
Baptism is a statement that the sinful person has been symbolically buried, then "resurrected" to a new life in Christ. Romans 6:4, "Therefore we have been buried with him through baptism into death, in order that just as Christ was raised from the dead through the glory of the Father, so we too may live a new life."