The description of Jerusalem continues without a break. Water is that universal symbol of life, that substance for which our bodies crave more strongly than any other.
The water of life is all that God communicates to the saints. It is the sum total of every blessing that comes from the infinite God to man. Behind all of these blessings is, as Gill says, the love of God. Love sends forth this great stream of life and is mixed with it. It is the same stream that goes out to us in this fallen world bringing us mercy and salvation in our lost state. It regenerates us and transforms us into the image of God. It reveals the Son of God to us through the Spirit, so that knowing him we have life. The same stream continues to flow in heaven, revealing new aspects of the divine nature and allowing us to drink ever deeper of the being and goodness of God. It is the Lord God himself, our exceedingly great reward. It is a river that brings life to the dead when we first encounter it and then continues to make that life flourish and grow in within us.