What concentration of hardness is considered hard or soft?
Concentration of hardness considered hard or soft.
There is no universal agreement on what exact concentrations are considered hard or soft. The following information was taken from the U.S. Department of Interior and Water Quality Association. Other organizations may use slightly different classifications:
|Classification||mg/L||gpg (grains per gallon)|
|Soft||0 - 17||0 - 1|
|Slightly hard||17 - 60||1 - 3.5|
|Moderately hard||60 - 120||3.5 - 7.0|
|Hard||120 - 180||7.0 - 10.5|