I live in south Florida where the municiple water is at best highly chlorinated and still somewhat mineralized. Most people will note immediately (If your not from here) that the Florida treated water has a sulferic or iron smell and taste. I never use it, I never boil it either.
I buy the water I brew with and in the local grocery store, the generic store brand gallon of water labeled; "Drinking Water" is safe and about $0.67/gal. Now, I know that at 5 gallons a batch per let's say every two weeks or so, this can add up. Well, I still brew eg so, it's not like I'm in this for the savings on beer.....My end calcs for brewing leave me with a wash on the price per case.
If I want to share it with others, I buy the water. I'm already at 50% on risk assesment on off-flavors before I even start a batch, so why hike it another 10-20% with nasty water?