Should I always use spring water for my brewing water?

Answer 1

I used spring water in my first two batches and was pleased with the outcome.  But then I spoke with an old brew buddy of mine and he convinced me to just use city tap water and I couldn't tell the difference in the final product.  

Not knowing the condition of the water coming out of your tap (you could be on well water or the city/county water is unbalanced) I'd be presumptuous to say "Just use tap water".  If your tap water has off flavors maybe you don't want to use it and stick to spring water.  

My experience is that the spring water will cost you more in the long run, you haven't gained much and you could have spent that money on more brew supplies.