Today's first reading and Gospel deal with our need for water and for the "living water" that Jesus offers us. Both sustain life, but Jesus quenches our thirst in a way that never needs replenishing. His love is always there for us at any point that we might need it.
Why then do we continually feel the need to question and test God? As mentioned in today's online homily, we are often like the Israelites in the first reading. Even after witnessing the miracles that led to them out of slavery in Egypt, they still questioned the power of God. We, too, often forget the miracles that have been done on our behalf. Worse, we often contribute them to mundane happenstances or even our own power rather than recognize the care that God has taken in our lives.
God provides us with living water, but so often we turn away and seek out temporary measures to quench our thirst. Often, we find gratification through means that even cause us harm rather than bring us life. Hopefully, in time we will recognize that God's path is not meant to restrict us, but to give us the nourishment that we need to live forever.