I have one of those Brita water filters. Just for kicks, I measured the PPM of my tap water and the PPM of a new filter, from 274 to 228. I was not impressed, and am strongly considering getting a reverse osmosis filter.
Also, I leave water out for 24 hours before running it through my Brita filer. I figure, if the chlorine evaporates on its own it's better to let the carbon focus exclusively on filtering particles.