Water Report help

My water report lists hardness as CaCO3, and states that this includes Magnesium and calcium. Is there a way to derive the amount of Calcium and the amount of magnesium from this number? Below is a link to the water report. Any help would be appreciated. Thanks in advance.

http://www.ccrwilmingtonde.com/2013_City_of_Wilmington_Water_Quality_Report.pdf

 

No. About the best you can do is take the 100 and assume that half comes from each. Fifty ppm calcium hardness as CaCO3 implies 20 mg/L calcium and 50 mg/L magnesium hardness implies 12.15 mg/L magnesium. The other thing you can do is add a couple of pearls of lye to a few mL of the water. If no precipitate forms then the water contains no (or very little) Mg and you can assume all the hardness is attributable to calcium.