“and let the one who believes in me drink. As the scripture has said, ‘Out of the believer’s heart shall flow rivers of living water.’” John 7:38
Jesus makes a seemingly odd statement: “Whoever believes in me, as Scripture has said, rivers of living water will flow from within them.” Yet, as it turns out, the statement isn’t so odd, because Jesus actually had much to say about the idea of water and new life.
Jesus tells the Samaritan woman that He could give her “living water.” This was in contrast to the physical water that the Samaritan woman came to the well to retrieve. That physical water would run out, and she would need to continually return to get more. But Jesus offered the woman water that would never run out—water that would become within the believer “a spring of water welling up to eternal life”
“but those who drink of the water that I will give them will never be thirsty. The water that I will give will become in them a spring of water gushing up to eternal life.” John 4:14
Jesus later would return to this theme when He stood up in public and said, “If anyone is thirsty let him come to Me and drink.” In this way, He was again offering Himself as the water of life and telling all they could come to Him and receive that never-ending life.
““Let anyone who is thirsty come to me, and let the one who believes in me drink. As the scripture has said, ‘Out of the believer’s heart[b] shall flow rivers of living water.’” John 7:37-38
After making the offer of life-giving water, Jesus adds that rivers of living water would flow from the heart of the believer
See also John 7:38, Isaiah 55:1 and Isaiah 58:11—passages that similarly present the Messianic hope in terms of life-giving water (cf. Exodus 17:1–6; Psalm 78:15–16; 105:40–41; Proverbs 18:4; Isaiah 12:3; Ezekiel 47:1–11; and Zechariah 14:8).
Jesus was not simply using metaphor to liken His own life-giving ministry to that of water. He was actually claiming to be the fulfillment of Scripture’s water allusions and prophecies. Because He was the Life-giver, those who believed in Him would have eternal life within them and would no longer need to seek for life from external sources.
“But you are not in the flesh; you are in the Spirit, since the Spirit of God dwells in you.” Romans 8:9
Later, in Romans 8:9, it is revealed that God would put His Spirit within each believer, and each believer would have eternal life (John 6:47) and the evidence of life (in the Holy Spirit) within. It is in that sense that “rivers of living water” would flow from the hearts of believers.
Believe in Jesus with all your heart, follow the Devotions of the Divine Mercy and become an spigot of this living water flowing from the Sacred Heart of Jesus through you into the thirsty world.