What is Water Hardness?

Water hardness represents total concentration of calcium and magnesium ions, reported as calcium carbonate.

Water Hardness Scale

Grains Per Gallon
 Parts Per Million (ppm)
 Classification
Less than 1.0
 Less than 17.1
 Soft
1.0 - 3.5
 17.1 - 60
 Slightly Hard
3.5 - 7.0
 60 - 120
 Moderately Hard
7.0 - 10.5
 120 - 180
 Hard
Over 10.5
 Over 180
 Very Hard