“Water” may be connected with procreation. This conception is quite foreign to us and we find it difficult at first to make sense of it. But Odeberg has gathered an impressive array of passages from rabbinic, Mandaean, and Hermetic sources to show that terms like “water,” “rain,” “dew,” and “drop” were often used of the male semen. If “water” has this meaning here, there are two possibilities. Being born “of water” may point to natural birth, which must then be followed by being born “of the Spirit,” that is spiritual regeneration. Or better, we may take “water” and “Spirit” closely together to give a meaning like “spiritual seed.” In this case being born “of water and the Spirit” will not differ greatly from being born “of the Spirit.”
The Greek word translated “born” means “conceived” when the father is in mind, and the ESV translates the same word as “conceived” or the like in Mat 1:2-16 (“was the father of” or KJV: “begat”), Mat 1:20 (“is conceived”), Acts 7:8, 29, 13:33 (quoting Psa 2:7), 1 Cor 4:15, Phile 1:10, Heb 1:5 (Psa 2:7 again), 5:5 (again). 1 John 3:9 speaks of being “born again” because “God’s seed abides in him,” and so the reference is really to conception (“seed” is a metaphor for semen).
In fact, given that Jesus was literally conceived by the Holy Spirit, and we are to be transformed into his image, it makes quite a lot of sense to speak of Christians being “conceived again” of the Spirit – like Jesus. And so this is a very likely translation of John 3:5. After all, Jesus is not likely to be thinking of God or the Spirit as the Christian’s spiritual mother. God is referred to as “Father” nearly 100 times in John’s Gospel.
The primary objection is Nicodemus’s reference to returning to his mother’s womb, but literal re-conception would also require a return to the womb. Jesus’ words are perfectly ambiguous as to whether he has birth or conception in mind, but several factors should point us toward the meaning “conception”: Jesus’ own conception (it was more precisely a virgin conception rather than a virgin birth, right?); John’s reference to the Spirit as “God’s seed” in 1 John 3:9; the countless references to God as a Christian’s “Father”; and the many references to Jesus as “only begotten” Son, based on Psa 2:7, which speaks of conception, not birth. Hence, we might take “water” as an allusion to “seed” or the Spirit as means of re-conceiving Christians or causing them to be newly begotten, just as Jesus was.
The hendiadys thus becomes “spiritual seed” or “spiritual semen.” I recognize that “semen” is a bit graphic for American tastes, but it’s the language we find in 1 Pet 1:23 and 1 John 3:9. Where the translators use “seed” to translate sperma, it’s a euphemism for God’s semen or sperm.
d. If Jesus’ point in saying that Nicodemus “must be born of the water and Spirit” was that baptism is essential for salvation, how could he (or John) say in the same discourse,
(John 3:16-18 ESV) “For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life. 17 For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him. 18 Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God.”
Any interpretation of John 3:5 that contradicts John 3:16-18 is surely in error.
In short, it’s not nearly as easy or as clear a question as many would argue. There are strong arguments on both sides. And if Jesus meant to say that salvation comes only by baptism, he sure found an odd context in which to say it (just before saying that everyone with faith will be saved) to an oddly chosen person (Nicodemus did not respond by asking for baptism but for a return to his mother’s womb) at an oddly chosen time (Jesus began his baptismal ministry afterwards (v. 22)) and in an oddly chosen location (Jesus wasn’t near the Jordan, where he would begin his baptismal ministry (v. 22)). Had Nicodemus desired baptism, he presumably would have had to follow Jesus down to Jericho along a very dangerous road, some considerable distance from Jerusalem – not because there was no water in Jerusalem but because Jesus didn’t baptize anyone until he left Jerusalem, most likely to baptize in the Jordan.
 BDAG, gennaō.
 Sperma can refer to literally semen, to inherited characteristics from the father, or descendants. But conception is always part of the picture. BDAG.
 Several passages that translate gennaō as “born” clearly intend to refer to conception. For example –
(1 Pet 1:23 ESV) since you have been born [conceived] again, not of perishable seed but of imperishable, through the living and abiding word of God.
Again, “seed” refers to semen or the male element of conception, and so “born again” should be translated “conceived again” or “begotten again” or even “re-fathered.”
Equally plain is –
(1 John 3:9 ESV) No one born of God makes a practice of sinning, for God’s seed abides in him, and he cannot keep on sinning because he has been born [conceived] of God.
And there are verses that speak of God as conceiving a Christian without explicit reference to God’s seed –
(John 1:12-13 ESV) 12 But to all who did receive him, who believed in his name, he gave the right to become children of God, 13 who were born [conceived], not of blood nor of the will of the flesh nor of the will of man, but of God.
Since the reference is to a child coming into being due to the will of the Father, conception is in mind, not birth.
(1 John 2:29 ESV) If you know that he is righteous, you may be sure that everyone who practices righteousness has been born [conceived] of him.
Again, the reference is to being “born” of God – our Father. Conception is the thought, not birth. This is yet another passage that associates re-conception with the Spirit (referred to as the Anointing in 1 John 2:27).
The ancients did not understand conception as the joining of egg with sperm. Rather, they thought of semen as “seed” that was “planted” in a “fertile” woman. Hence, inheritance generally passed via the sons, as only the sons could pass along the “seed” of their fathers. To be begotten of God would thus not only make one an heir of God but also take on his characteristics by inheritance. Being “born” of God would accomplish neither as no one inherited from his or her mother.
First Century and earlier Judaism had no practice of adoption. There was no Hebrew word for “adopt” until the 20th Century. Barbara T. Blank, “Jewish Adoption in America,” My Jewish Learning. http://www.myjewishlearning.com/article/jewish-adoption-in-america/
Hence, in Psa 2:7, when God declares that he has become the Father of the Messiah, he speaks in terms of having “begotten” him. The Romans practiced adoption, considering adoption to make one an entirely new person in the eyes of the law, so that even the son’s old debts would be forgiven when he was adopted. Thus, to a Hellenistic or Roman audience, Paul can use adoption as a metaphor for salvation. Among Jews, salvation is pictured as gaining a new father by being re-begotten, based on Psa 2:7 and our likeness to Jesus in his being re-begotten by the Spirit.
 Translators differ as to whether Jesus said these words or Jesus’ discourse ended earlier and these are the words of John. They are just as inspired either way, and if it’s John speaking, he’s commenting on what Jesus had just said to Nicodemus.
 The text says Jesus was in the Judean countryside. Jerusalem sits atop Mounts Zion and Moriah. There’d be very few places suitable for baptisms between Jerusalem and the Jordan River to the east. To the north was Samaria, where Jews usually did not travel. To the south is desert. Jesus might have gone to the west, to the fertile coastal plains. But the symbolism of the Jordan River would have been powerful, as this was the entry into the Promised Land. 3:26 tells of a disciple complaining to John the Baptist about Jesus’ baptizing, while John was in Aenon, near the Jordan, to the north of Jerusalem. It would have been very natural for a disciple of John to travel along the Jordan and so come across Jesus on his way to see John if Jesus was baptizing in the Jordan. Moreover, the Jordan is on the way to Galilee, Jesus’ next stop (4:3), as Jews normally walked around Samaria along the Jordan when traveling between Galilee and Jerusalem.