In its seventh chapter, the Didache reads, “Concerning baptism, baptize in this manner: Having said all these things beforehand, baptize in the name of the Father and of the Son and of the Holy Spirit in living water [that is, in running water, as in a river]. If there is no living water, baptize in other water; and, if you are not able to use cold water, use warm. If you have neither, pour water three times upon the head in the name of the Father, Son, and Holy Spirit.”
…
Hippolytus of Rome said, “If water is scarce, whether as a constant condition or on occasion, then use whatever water is available”
…
Pope Cornelius I wrote that as Novatian was about to die, “he received baptism in the bed where he lay, by pouring”
…
Cyprian advised that no one should be “disturbed because the sick are poured upon or sprinkled when they receive the Lord’s grace”