Dear Heather,

The practice of mixing water and wine has both a practical and symbolic meaning.  During the time of Christ most wine would be cut with water anyway, I guess it was a little too strong or sweet  for most people's tastes.  In Liturgy, this practice continued to the present time even though in the secular world it stopped.  It continued in Liturgy because for Christians, the mixing also has a symbolic reason since as scripture records when the side of Christ was pierced by the soldiers, both blood and water flowed out.

Hope this helps,

Mr. Slavek