Schaff, Philip. "Baptism in the Didache." The Oldest Church Manual Called the Teaching of the Twelve Apostles. Second Edition, Revised and Enlarged. New York: Funk & Wagnalls, 1886, 29-35.
The baptismal directions in the Didache have attracted a good deal of attention, especially in the United States. In chapter seven, the instructions specify running water if possible, preferably used for immersion, but if not, pouring is sufficient (Schaff 1886, 30). Schaff compares this to the instructions in Justin Martyr's Apoloty 1.61.
Schaff observes that in the Didache baptism takes place after instruction. This assumes "catechumens, or adult believers" (Schaff 1886, 31). Schaff notes that in places where the Gospel is new, the norm is adult converts. However, within Christian families it has been very common, dating back at least to the second century and likely further.
Baptism is in the triune name of God (Schaff 1886, 31), and is normally by immersion, suggested by the distinction in the allowance of pouring (Schaff 1886, 32). There are early accounts of a triple immersion, which Schaff assumes in the Didache as well. Exceptions to immersion in running water were "other water" or "warm water" if necessary, or by pouring over the head if there was not enough water. "Here we have the oldest extant testimony for the validity of baptism by pouring or aspersion" (Schaff 1886, 33). There was clear acceptance of immersion or pouring . Schaff sees this as reason that disputes about the mode of baptism should stop (Schaff 1886, 34).
Baptism is preceded by a fast of one or two days. Schaff observes that there is no such regulation in the New Testament but that Justin Martyr and Tertullian do mention it. The Didache is more definite in its expectation (Schaff 1886, 35). Schaff sees in the lack of an exorcism or chrismation, and in the fact that the baptism belongs to the congregation rather than a bishop, evidence that the Didache is an early work.