Carmel: In this case water does not signify material water, for elsewhere it is explicitly said baptism is with spirit and with fire, from which it is clear that the reference is not to material fire and material water, for baptism with fire is impossible.
You might also benefit by a consideration of the verses I cited. After Cornelius' household received the indwelling of the Holy Ghost, Peter asked "Can any man forbid water, that these should not be baptized, which have received the Holy Ghost as well as we?"—Acts 10:47
Also, Acts 2 shows "a sound from heaven as of a rushing mighty wind" and "cloven tongues like as of fire" appearing visibly over the heads of 120 disciples. While the fire of baptism is symbolic, its symbolism is not left a mystery.
Judges 15:14 And when he came unto Lehi, the Philistines shouted against him: and the Spirit of the LORD came mightily upon him, and the cords that were upon his arms became as flax that was burnt with fire, and his bands loosed from off his hands.
Isaiah 30:27 Behold, the name of the LORD cometh from far, burning with his anger, and the burden thereof is heavy: his lips are full of indignation, and his tongue as a devouring fire: 28 And his breath, as an overflowing stream, shall reach to the midst of the neck, to sift the nations with the sieve of vanity: and there shall be a bridle in the jaws of the people, causing them to err.
1 Thessalonians 5:19 Quench not the Spirit.
(NIV) 2 Timothy 1:6 For this reason I remind you to fan into flame the gift of God, which is in you through the laying on of my hands. 7 For God did not give us a spirit of timidity, but a spirit of power, of love and of self-discipline.
The water, on the other hand, was not symbolic in its own nature, while the act of baptism in it was symbolic. This is evidenced by the repeated references to a literal body of water and baptism in literal water and the absence of any recorded "symbolic" water for baptism.