One thing I wonder about in the NTMWD reports is why they report the same number for bicarbonates(HCO3) in ppm and for total alkalinity as CaCO3. AFAIK, these are supposed to be in a 61/50 ratio (HCO3 to alkalinity). They started doing this in Sept., 2009 - prior to that the reported numbers were in the 61/50 ratio. A couple of years ago I tried to contact the NTMWD but couldn't get hold of anyone who knew the answer. I've also posted the question in the Brew Science forum, but never got an answer.