The Psalms are filled with references to thirst and water. Think of where the Bible was written. The Middle East is mostly deserts, so water is a precious commodity. The Lord sustains life, and with water being scarce, God giving his believers water is an apt metaphor that explains what His love does for us. It quenches and nourishes us when we most need it.
And we pray:
I am thirsty, my Lord, and I know that You will provide me, as You always have. Give me this day my daily bread, and allow me to drink from Your cup of faith. You are the only and one true God, and I rejoice in knowing You. I am humbled by this relationship, and pleased to know that with each day I become closer to You. Walk with me, O Lord, hand in hand, so that we may spread Your Love throughout the land. Amen.