When I first installed my RO machine a few years ago, I had both my tap water and RO water tested at Ward Labs. Here were the results:
Tap pH 7.4, TDS 222, Ca 11, Mg 4, Na 46, SO4-S 5, Cl 67, Bicarb HCO3 19, Alk CaCO3 15
RO pH 7.8, TDS 26, Ca <1, Mg <1, Na 6, SO4-S <1, Cl 7, Bicarb HCO3 3...