REQUIREMENT 2 OF A VALID CATHOLIC SACRAMENT: CORRECT MATTER
The Catholic Rite of Baptism has three requirements: Proper Form, Matter & Intention. The correct matter is simple: plain water. Stay away from Vatican II 'Holy Water', it is not required nor beneficial to your salvation. Albeit obvious, there were some in church history who theorized that in the absence of clean water, beer, for example may be substituted, which is why this requirement is mentioned. It is ridiculous to bother explaining this requirement any further, it should suffice to understand that the correct matter for valid Catholic baptism is plain water which is widely available. It is much more important to concentrate your effort on understanding the Form and Intention, though we provide dogmatic evidence of this requirement simply for the sake of being as thorough as possible.