I don’t really know much about water chemistry, but from what I understand
some water is better suited to lighter beers and some towards darker beers.
If my water is better suited for pale ales (I don’t know if it is) and I brew a stout with no mineral additions
what would the flavor difference be?
When we talk about a given water being better suited to light or dark beers, it generally doesn’t involve flavor. We’re mostly concerned with residual alkalinity (RA) - since darker grains are more acidic in the mash, you need higher RA to balance it out. If the RA is too far off, the mash pH can get out of the desired range and affect conversion (and to a lesser extent flavor).
There’s a pretty involved discussion active in the All Grain subforum: http://www.homebrewersassociation.org/forum/index.php?topic=3195.0
In a nutshell, the darker beers would have a harshness to them. It might be to a lesser or greater degree depending on exactly what your water is like. I know that my dark beers have improved greatly since I started adjusting the mash with CaCO3.
If you are using water from a local utility then a water report might very well be available online. It would behoove you to look for it. If you get your water from a well then you can send in a sample to Ward Labs.
I was never happy with my All Grain based beer until the water issue got sorted out.
The local water report that is available seems to just list contaminants.
I was thinking of calling them to see if hey would give me the info that I need.
If I do call them is this what I should ask for.
Calcium (Ca+2),
Magnesium (Mg+2),
Bicarbonate (HCO3-1)
Sodium (Na+1),
Chloride (Cl-1)
Sulfate (SO4-2)
Is there anything else I need to know?
Looks good. Hopefully they won’t go “huh?”
I’m lucky enough to get a very detailed one from the primary water utility for the metropolitan area, but my small local utility (the exact same water) only lists contaminants. Losers. 
Denny,
I see that you add CaCO3 to your mash. Just curious, is the water in your part of Oregon soft as here in Bend? I will be brewing the Oatmeal Stout this weekend. According to the http://www.ezwatercalculator.com/ an addition of chalk would help with my low residual alkalinity. Also, some say to simply add the dark malts to the last 15 mins of the mash.
Thanks
It’s fairly soft, but my well water has more mineral content than the water in Eugene or PDX. I don’t know what Bend water is like. Try adding some CaCO3 to your dark beer mashes and see if it helps.
Thanks Denny. Do you have any difficulty getting it to dissolve in the mash?
Not at all.
I have pretty soft water here in Redmond (near Seattle), and just last week I decided to brew a stout with some chalk thrown in the mash. I had never previously noticed any harshness from my stouts but I thought if I can make them better with some chalk I’ll give it a shot… So I’m excited to see how this one turns out. I wonder if Deschutes adds chalk to their Obsidian Stout… hmm… to potentially answer my own question… from my notes on the Can You Brew It? Obsidian Stout recipe I have written that just a little gypsum is added…
I think you will find that very few commercial brewers use chalk ever.
That would be quite unusual.
Indeed, but that is what Jamil has in the CYBI recipe FWIW…