Charles Ellicott Commentary 1 Kings 18:33

"And he put the wood in order, and cut the bullock in pieces, and laid it on the wood. And he said, Fill four jars with water, and pour it on the burnt-offering, and on the wood." — 1 Kings 18:33 (ASV)

Fill four barrels —or pitchers. The filling of these during a time of drought has naturally aroused speculation.

A common assumption by those unfamiliar with the region was that the water was taken from the sea flowing at the base of Carmel. However, a look at the mountain's position and height rules out this understandable assumption, as such an act would have been difficult, if not impossible. Examination of the area has discovered a perennial spring in the vicinity of the traditional site of the sacrifice, which is known never to fail even during the most severe droughts.

Undoubtedly, from this spring (as Josephus indeed explicitly states) the water was drawn. This was done, of course, with the clear purpose of preventing any suggestion of fraud or trickery and powerfully highlighting the consuming fierceness of the fire from heaven, which is so emphatically described in 1 Kings 18:38.