Zabadak, you're making it up again. The 'witness' was no more insistent on the water and blood than on any other aspect of the event. He simply related the story. I think it far more likely that 'John' overlooked, or was unaware of, the changes that occur to a body upon death, and made the mistake of adding that bit in order to fulfil the old prophecy - just as many of the other texts were changed (or indeed written) in order to fulfil the prophecies of the Old Testament.
Additionally, you make the spurious claim that the lance stroke was in the region of the heart when as far as I'm aware (without checking), we don't know which side was pierced, and we have no idea of precisely where the blade entered the body, or at what angle. Your theory is purely surmise.
By the way, I never dismiss documents just because they're faith based. I believe people who do that are making a huge mistake.