In I Samuel 7:6, we read that when Israel gathers at מצפה, they וישאבו מים וישפכו לפני יי.
Usually at these sorts of gatherings there are animal sacrifices, not water libations. It is slightly reminiscent of אליהו בהר הכרמל but the water there was not the sacrifice itself, but to make the burning by the fire from heaven more dramatic. Or at least that’s how I always read it. Perhaps in light of what we read here in Samuel there is more to the water itself?