Just out of curiosity, some one told me not too long ago that I could buy water at the store that's already high in certain minerals, and it's good for brewing dark beers. Which leads me to believe it has a decently high bicarbonate in it. I have a multitude of questions about this. does anyone buy this water themselves and continue to build it up for their stouts and porters? If so, how do you know the mineral content of that high mineral water? Can I buy this at Whole Foods or some other fancy grocer? I looked at my local grocery and they didn't sell it. Is this worth it? The only reason I want it is because it might have a good amount of carbonate in it... I can't necessarily build up from DI water because too many baking soda additions will skyrocket my Sodium levels, and I don't have a way to dissolve chalk at this point in my brewing life. any suggestions?