מלכים א, פרק י״ח, פסוק ל״ה

The sheer volume of water poured over the sacrifice serves to highlight the extraordinary nature of the miracle about to take place. The water did not merely soak the offering; it flooded the entire surrounding area. Because the wood and the sacrifice were positioned exactly in the center of the altar, the water poured over them naturally cascaded downward. As it spilled off the sides, it completely encircled the entire structure of the altar and the arranged wood [רד״ק, מצודת דוד].

Beyond the flooding of the altar itself, the surrounding trench was also filled with water. The primary approach among commentators is that Elijah either filled this trench himself or instructed others to do so on his behalf [רד״ק, מצודת דוד]. This water was entirely new and additional, brought in specifically to fill the trench, completely separate from the twelve jars of water that had already been poured over the burnt offering and the wood [רד״ק].