The three broke through the host of the Philistines, and drew water out of the well of Bethlehem, that was by the gate, and took it, and brought it to David: but David would not drink of it, but poured it out to Yahweh,
And so he poured the water out on the ground because he just felt unworthy to drink that water. He felt that those guys that were willing to hazard their lives for a thing like that better that they give it to the Lord. So he poured it out to the Lord, verse eighteen.