From time to time some Christians tell other Christians that their baptism was not valid because it was not done by full immersion, the only way Jesus authorized people to be baptized. The claims sometimes go on to claim that “sprinkling” was an invention of the Catholic Church in the 4th century when people began to flood into the church and it was just more efficient that the required full immersion.
There is no doubt that full immersion baptism was practiced, but even in the 1st century it was not the only way baptism was celebrated. The Didache, an anonymous Christian treatise that dates between the years 65 and 80 AD, gives specific instructions as to where baptism should take place.
And concerning baptism, baptize this way: Having first said all these things, baptize into the name of the Father, and of the Son, and of the Holy Spirit, in living water. But if you have not living water, baptize into other water; and if you can not in cold, in warm. But if you have not either, pour out water thrice upon the head into the name of Father and Son and Holy Spirit. But before the baptism let the baptizer fast, and the baptized, and whatever others can; but you shall order the baptized to fast one or two days before.
This early instruction explains that baptism could be administered through full immersion in a river or other “living water,” or it could be done by simply pouring water three times over the head. Both forms were valid and used depending on the situation.