Matthew Poole and continuators on Leviticus 14:5

5 And the priest shall command that one of the birds be killed in an earthen vessel, over running water .

To wit, by some other man. The Priest did not kill it himself, because it was not properly a sacrifice, as being killed without the camp, and not in that place to which all sacrifices were confined; and if it had been a sacrifice, that might be killed by another, so long as the sprinkling of the blood of it, which was the most proper and essential act in the sacrifice, was done by the Priest.

It seems to be a Metathesis or transplacing of words for, over-running water put in an earthen vessel. Thus the blood of the bird and the water were mixed together, partly for the conveniency of sprinkling, and partly to signifie Christ who came by water and blood, 1 Iohn 5. 6. The running water, i. e. spring or river water by its liveliness and motion did fitly signifie the restoring of liveliness to the leper who was in a manner dead with his leprosie, as was noted before.

Marginal references: Heb. living water. Gen. 6. 29.