I recently moved from Madison, WI to Rome, Italy and I'm having some issues with my brewing water.
While previously living in Madison, WI I transitioned from brewing with my tap water to brewing with reverse osmosis water due to the fact that the tap water was very high in alkalinity and it was having a detrimental impact on the flavor of my beer and my mash efficiency.
Now that I'm in Rome I have less mobility as I am without a car, and I decided brewing with the tap water was the only way to go. The following is a copy of a report of the water I'm working with:
Ca: 101.2 ppm
Mg: 17.5 ppm
Na: 7.0 ppm
SO4: 17.4 ppm
Cl: 9.1 ppm
HCO3: 398 ppm
As you can see, the water is VERY high in bicarbonate. The first couple of brews that I've done I've adjusted my water with lactic acid to achieve my desired pH for mashing. As a result, all of the beers I've brewed this way have that lactic "twang."
After thoroughly reading Martin's wonderful post on 'Decarbonation by Boiling,' I've decided to go that route. Using Martin's formula, my calculations indicate I should have enough Calcium to reduce the bicarbonate from 398 ppm to ~90 ppm assuming all of the Ca is converted to CaCO3. Does this seem reasonable?
Secondly, I did a bench top test by boiling 1 L of tap water in a small pan and I'm finding that after cooling the pH of the water increases from around 7.5 from the tap to 7.9 after boiling. Is this normal?
Any other advice? Thanks.
Side Note: I'm filtering the tap water through an activated carbon filter to remove chlorine.