Jesus was NOT talking about baptism, nor did He say, "born again of water", as you have misquoted. He was simply comparing natural birth to spiritual birth, that we need both. "Born of water" is one's flesh birth, and "born of the spirit" is the new spiritual birth by faith.
John 3:3-8
Jesus replied, “I tell you the truth, unless you are born again, you cannot see the Kingdom of God.”
4 “What do you mean?” exclaimed Nicodemus. “How can an old man go back into his mother’s womb and be born again?”
5 Jesus replied, “I assure you, no one can enter the Kingdom of God without being born of water and the Spirit. 6 Humans can reproduce only human life, but the Holy Spirit gives birth to spiritual life. 7 So don’t be surprised when I say, ‘You must be born again.’ 8 The wind blows wherever it wants. Just as you can hear the wind but can’t tell where it comes from or where it is going, so you can’t explain how people are born of the Spirit.”