Jesus’ cry of “I thirst” from the cross teaches us much about who he is. It shows his humanity, but in the way that John records it he also emphasises how it proved that he is the Christ, the Son of God. In the light of what John records about water and thirsting elsewhere it also reminds us that it is only in Christ that true satisfaction is found.

The Death of Jesus
28 After this, Jesus, knowing that all was now finished, said (to fulfill the Scripture), “I thirst.” 29 A jar full of sour wine stood there, so they put a sponge full of the sour wine on a hyssop branch and held it to his mouth.

John 19:28-29 English Standard Version (ESV)