In the US domestic water treatment industry, water hardness is often reported in grains per gallon. One grain per gallon is equal to 17.1 mg/l.
"Acidity" of water is expressed in pH units. It is the logarithm of the reciprocal of the hydrogen ion concentration [H + ] in the solution. For pure water the hydrogen concentration is 1 x 10 -7 moles per liter and the solution can be characterized as pH 7. The pH can range from 0 to 14, but most potable water will range from 6.5 to 8.5. Any solution with a pH below 7 is acidic; any solution with a pH above 7 is alkaline.
If you have your water tested for a broad range of substances, do not
be surprised if a lot of things are found and reported. Compare results
with accepted standards and nuisance levels discussed previously before
becoming overly concerned. If a problem is found or confusion as to the
meaning of the results develops, then a water quality treatment expert
should be consulted. Your local health department office should be notified
if a standard MCL is exceeded. These agencies as well as private water
treatment companies can be contacted for specific treatment recommendations.