Elaine, I never even considered tap water being an advantage rather than a disadvantage when growing plants. Most everyone over the years has really beat the drum about how bad chlorinated water is for plants and how successful they are using rainwater. I have always used tap water but never had the courage to tout my use of it.
I just thought I must be lucky or have some "magical" tap water, since I grow well over 500 plants from seedlings each and every year. Hurray for chlorinated water.