What is the primary use of a water softener?

The primary use of a water softener is to reduce hardness in water by lowering the concentrations of calcium and magnesium. Hard water contains high levels of these minerals, which can create issues such as scale buildup in pipes and appliances, reduced soap and detergent effectiveness, and potential stains on laundry and fixtures. A water softener typically employs a process called ion exchange, where hard minerals are exchanged for sodium ions, resulting in softer water that is easier to manage and use for household tasks.

Filtering microorganisms from water addresses a different concern related to water safety and quality, which is not the function of a water softener. Increasing water temperature is a separate process that involves water heating technologies, and maintaining water pressure is related to plumbing systems rather than the function of a water softener. Therefore, the reduction of hardness specifically through the removal of calcium and magnesium makes the chosen answer the most accurate.