Human beings are full of fears, especially from each other. Also, mountains and tall buildings and roaring waters and oceans are also quite scary. But a Y'rei Shamayim who feels only Hashem, makes a Bittul (belittling) of the entire universe, since it’s all zero compared to Hashem. Vatitatzav achoso merachok, Moshe’s sister, Miriam, stood near the water to watch what would happen to him” teaches us clearly that Miriam wasn’t Nis'pael from the danger of water.
And this is despite the Gadol HaDor (her father) Amram’s fear. Now we understand why the Be’er (water) was in the Zechus of Miriam. The one who isn’t fazed by dangerous water, and realizes that water is only a mere creation of Hashem which is totally in Hashem’s control and has no real essence of its own, is Zoche to get as much water as needed to supply the entire Klal Yisroel.
