I guess the answer begs the question…what’s your beginning water chemistry before its filtered? With municipal water…particularly in my area, the water changes occasionally…sometimes pH, PPM, and chlorine content. I havent had it tested but i know if I was to test it say quarterly, it would be a bit different each time.
What would you prefer? RO or Charcoal?
Another question…if you used RO water but wanted to add back only one “prescribed” chemical additive for a decent range of beer styles to benefit them all…what would it be?