a [born of water and of the Spirit] Not the natural birth, for Nicodemus already had this birth and he was told he had to be born again of both water and Spirit.

Not water baptism; all Old Testament saints were saved and born again without water baptism (Heb. 11; Rom. 3:23-25; Heb. 9:15; Rom. 4; Gal. 4:29; Jas. 2:23; Ps. 32:5; 103:3; Lk. 1:70; Acts 3:21; Dt. 32:18; 2Pet. 1:21).

They all had the Holy Spirit, gifts, and many blessings without water baptism (Ps. 51:12; 1Ki. 3:12; 4:29-34; Num. 11:17-29; Acts 3:21; Lk. 1:15-17,41,46,67; 2:25-38; Heb. 11).

Many in Christ's ministry were forgiven without water baptism (Mt. 9:1-7,22; Mk. 5:34; 10:52; Lk. 7:48; 17:19; 18:9-14; 19:1-9; 23:43; Jn. 4:49-53; 7:31; 8:30-31; 11:45; 12:11,42). Men have been baptized in the Holy Spirit before water baptism(Acts 9:17; 10:44-48; 11:14-18; 15:7-11). Christ was baptized in water without forgiveness of sins (Mt. 3:15-17).

It is a mere figure (1Pet. 3:21) and a witness (1Jn. 5:6-10), but not held as essential to salvation (1Cor. 1:13-24; 15:1-5; Rom. 1:16; 10:9-14; Eph. 2:8-9; Acts 10:43; 13:38-39; 16:31; Jn. 3:14-18,36; 5:24; 1Jn. 5:1). It is only for men who have repented (Mt. 3:2-6; 28:19; Acts 2:38-41; 8:12,37; 10:43-48; 18:8; 19:4).

Water is used in a figurative sense of salvation (Jn. 4:14; Isa. 12:3), of the Spirit baptism (Jn. 7:37-39), and of cleansing by the Word of God (Jn. 15:3; Eph. 5:26).

Since men are cleansed and born again by the Word (Jas. 1:18; 1Pet. 1:23), it is clear that being born of water means being born again by the Word of God.
Dake's Annotated Reference Bible.