In using the the images of God as water/food, the Bible is evoking God as the satisfaction of our most intense desires. For, what do we desire more intensely than food/water? It's not just that we need them, but that we need them intensely. We crave them when thay are absent. Now, given that I am made for God, then intensity of desire for God is really one of the most natural things in the world. Spiritual intensity is a work of the Spirit of my life and I need to do everything I can to promote it. For, the intensity of my desire, or lack of intensity, reveals my appreciation, or lack of appreciation, of who the Lord God really is.
"For me, to live is Christ, to die is gain" (Philippians 1:21)
"O God, you are my God, earnestly I seek you; my soul thirsts for you, my body longs for you, in a dry and weary land where there is no water" (Psalm 63:1)
“O my Sweet Saviour! Whom have I in heaven but thee? And there is none upon earth that I desire beside thee. If I had a thousand lives, my soul would gladly have laid them all down at once, to have been with Christ.” (David Brainerd)