Seattle has excellent water for brewing as there is little in terms of metals, minerals, or hardness, and it has a pH around 8, making it a good base to start for any beer type. You may need to add minerals and some acid depending on the type of beer to improve mash efficiency and hop flavor (read the water primer FAQ).
Detailed water quality (including Ca, pH, alkalinity, etc)
As acidrain says, you should dechlorinate your water as SPU adds chlorine for disinfection.
Old, corroding pipes are probably your only concern, but if the water tastes fine out of the tap, then it won't taste funny after being brewed because the yeast will scavenge trace amounts of copper and other metals or minerals during the fermentation.