Overview Data Input Data Output DIC Charge Balance Physico-Chem Params Reactions Redox Mineral Phases

Soft and Hard Water

The U.S. Geological Survey recommends the following classification into hard and soft water (based on Total Hardness TH):

Water Type	TH in ppm CaCO3	TH in °dH	TH in mM	TH in meq/L
soft	< 60	< 3.35	< 0.6	< 1.2
moderately hard	60  to  120	3.35  to  6.7	0.6  to  1.2	1.2  to  2.4
hard	120  to  180	6.7  to  10.05	1.2  to  1.8	2.4  to  3.6
very hard	> 180	> 10.05	> 1.8	> 3.6

This classification is used by aqion to categorize aqueous solutions into four water types. One example of a moderately hard water is shown in the right screen shot.

See more examples here.