What calcium measurement for hard and soft water?


Well-known member
Apr 29, 2016
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.


LifeTime Supporter
TFP Guide
Feb 6, 2015
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