I had never noticed before today the pervasiveness of the theme of water (hydor) in the opening chapters of John. I'm wondering if water is the dominant metaphor for the first half of the pre-passion narrative (ch. 1-7), light the dominant motif of the second half of the pre-passion narrative (8-12), and love that of the passion narrative (13-21). John 1 messes up my theory, though, with no mention of H2O but lots of mention of light. Anyhow . . .
John 2 - Jesus turns water into wine
John 3 - Jesus tells Nicodemus he must be born "of water and the Spirit," and late in the chapter (v. 23) speaks of the "plentiful" water where John was baptizing
John 4 - an extended discussion between Jesus and a Samaritan woman about literal water vs. that which prevents any future thirst
John 5 - the rather sad character, lame for 38 yrs, lying at the pool complaining of having no one to help him into the water (v. 7) (also, the variant which includes v. 4 mentions the pool's hydor 3x)
John 6 - Jesus walks on water
John 7 - as in ch. 4, Jesus reiterates that those who believe in him will have springs of living water flow from the inside-out
Water shows up two other times in the narrative, in ch. 13 where Jesus pours water into a basin and washed the disciples' feet, and ch. 19 where blood and water come out of his side when pierced with a spear. Probably too much to work these in somehow, but I think it is definitely a controlling motif in the first 7 chapters. Remembering the value water held in that dry, pre-plumbing culture is of course integral too.