John Gill Commentary 1 Kings 18:35

"And the water ran round about the altar; and he filled the trench also with water." — 1 Kings 18:35 (ASV)

And the water ran round about the altar
There being such a large effusion of it on it;

and he filled the trench also with water ;
which surrounded the altar, so that it seemed impracticable that any fire should kindle upon it; and this gave full proof and demonstration there could be no collusion in this matter.