What calcium measurement for hard and soft water?

Sjde

Well-known member
Apr 29, 2016
209
Denver CO
Out of curiosity I tested my tapwater and it was only 20 ppm calcium . Then I got online to see what the measurements were for hard and soft water and I could not find anything that listed it in parts per million.
 

proavia

LifeTime Supporter
TFP Guide
Feb 6, 2015
1,514
Chandler AZ
Many times you will see water hardness shown in grains
Divide ppm by 17.1 to get grains
20 ppm / 17.1 = 1.17 grains
Pretty darn soft