Water Hardness

\[Hardness=2.497Ca+4.118Mg\]

Variables

Hardtotal hardness as CaCO3 (mg/L)

Cacalcium concentration (mg/L)

Mgmagnesium concentration (mg/L)

Description

What is this formula?

This formula estimates total water hardness as calcium carbonate from calcium and magnesium concentrations.

When to use it

Use it when evaluating drinking water, groundwater, boiler water, cooling water, irrigation water, pools, and industrial process water.

Example

Data:

Ca = 60 mg/L

Mg = 18 mg/L

Formula:

Hardness = 2.497Ca + 4.118Mg

Substitution:

Hardness = 2.497(60) + 4.118(18)

Result:

Hardness = 224.1 mg/L as CaCO3

Applications

Water treatment, drinking water quality, boiler and cooling tower management, scaling control, groundwater studies, irrigation water evaluation, and pool chemistry.

Note

This is a standard conversion-based estimate. The coefficients convert calcium and magnesium concentrations expressed as mg/L of Ca and Mg into equivalent hardness as CaCO3. Results depend on accurate ion concentration measurements.