For a discussion of hardness, see Hardness (calcium).
This method is applicable to drinking, surface, boiler,and brine waters.
The EDTA titrant is employed in alkaline solution
with a calmagite indicator. This method determines the combined calcium
and magnesium concentration of a sample. If no magnesium is present, the
end point of the titration normally appears sluggish. However, the reagent
has been specially formulated to ensure a sharp end point regardless of
the presence of magnesium. Results are expressed as ppm (mg/L) CaCO3.