In truth, the water doesn't have to be anything special. It could be from the Jordan River, or it could be from the kitchen sink. In other words, it is just ordinary water.
In some ways, the word that goes with the water is both ordinary and extraordinary. In baptism, what we say is really a fulfillment of God's promises to us. If these are simply read and there is no action, they remain rather ordinary. But when they are spoken over the water and the one being baptized, they become true again and again. God is good!