Yes, water quality matters a lot in coffee enthusiast land. They actually make little mineral packets that you add to a gallon of distilled water to get a "perfect" brewing water - I know since I actually use them for my espresso machine to fight scale buildup from my +10 grain tap water.

Note this excessiveness is really needed for espresso though; a regular Brita jug handles more tolerant methods of brewing perfectly well (and to be honest most people murder coffee enough that the water is the least of their concerns)