Water Hardness Calculator

The water hardness calculator is the tool you need to estimate the amount of dissolved minerals present in your tap water supply. Minerals like calcium $(\mathrm{Ca^{2+}})$ and magnesium $(\mathrm{Mg^{2+}})$ are often present in your regular water supply. They often have health benefits. However, they can also cause issues like scaling in pipes, boilers, and heaters clogging, and/or reducing the efficiency of the apparatus. Read on to understand how to calculate the hardness of the water.

It is important to remember that the water hardness is different from the hardness of a metallic surface (Brinell hardness number calculator).

Water hardness is the parameter used to measure the dissolved minerals like calcium and magnesium in water. Based on the value of water hardness, water is classified as hard or soft. Hard water is common in the areas where gypsum, limestone, and chalk are found in the ground. The hardness of water is measured in the units mg/L (milligrams per liter), ppm (parts per million), or mmol/L (millimoles per liter). The formula to calculate the hardness of water (in mg/L) can be written as:

where Cal and Mg are amounts of calcium $(\mathrm{Ca^{2+}})$ and magnesium $(\mathrm{Mg^{2+}})$ in mg/L, respectively.

Based on the value of hardness, the water is categorized as hard or soft:

To calculate the hardness of water, follow the steps below:

1. Enter the value of calcium concentration in mg/L.
2. Enter the value of magnesium concentration in mg/L.
3. The water hardness calculator will now return the hardness value in mg/L of $\mathrm{CaCo_3}$.

Estimate the water hardness of the supply having a calcium concentration of 31 mg/L and a magnesium concentration of 27 mg/L.
To estimate the hardness of water:

1. Enter the value of calcium concentration as 31 mg/L.
2. Enter the value of magnesium concentration as 27 mg/L.
3. Using the water hardness calculator:

The water hardness value is $188.6~\mathrm{mg/CaCo_3L}$. Based on the hardness scale, the water is very hard.

There are two types of water hardness — temporary and permanent. The classification is based on the presence of different metallic compounds.

• Permanent hardness — Contains calcium sulfate $(\mathrm{CaSO_4})$/ calcium chloride $(\mathrm{CaCl_2})$ and/or magnesium sulfate $(\mathrm{MgSO_4})$/ magnesium chloride $(\mathrm{MgCl_2})$.
• Temporary hardness — Due to the presence of bicarbonate compounds like calcium bicarbonate $(\mathrm{Ca(HCO_3)_2})$ and magnesium bicarbonate $(\mathrm{Mg(HCO_3)_2})$.

Permanent hardness can be removed by boiling the water or running the water through an ion-exchange column, whereas temporary hardness can be removed by boiling the water or using lime (calcium hydroxide — $(\mathrm{CaHO_3})$. The idea is to precipitate the compounds out of the solution and then take out the soft water once cooled.

Regular exposure to hard water can lead to scaling in pipes, leading to energy loss in pipes. Learn more about that with our friction loss calculator and pipe flow calculator.