Which process is commonly used to remove hardness from water?

The process commonly used to remove hardness from water is ion exchange. This method involves exchanging ions in the water that cause hardness, primarily calcium and magnesium ions, with sodium or potassium ions which do not contribute to hardness.

Ion exchange systems typically use a resin that is charged with sodium ions. As hard water passes through the resin, the calcium and magnesium ions bind to the resin, displacing the sodium ions. The result is softened water that can be used for various applications, such as in boilers and cooling systems, where hardness can lead to scaling and other issues.

Other processes, such as filtration, are used for removing particulates and sediment but do not specifically address the chemical components that cause hardness. Distillation can also reduce some hardness but is less efficient and practical for large volumes of water. Evaporation does not effectively remove hardness ions, as these remain in the water. Thus, ion exchange is the most effective and widely used method for softening water and removing hardness.