I live in a Chicago suburb and our water is from Lake Michigan. Many brewers here like that water, so I use it from the tap. I have used a carbon filter, but that was a while ago. I do let my water sit out to get rid of the chlorine and I add campden to counter the chloramines (spelling?). You could also order a report on your water and get an analysis on it. I think if you look in the science forum here on HBT you'll find more info about that.