The answer to 'what causes water softener' is that a water softener is used to remove minerals like calcium and magnesium from hard water. Hard water can cause buildup in pipes, appliances, and on fixtures, leading to reduced efficiency and lifespan. A water softener uses an ion exchange process to replace these minerals with sodium, softening the water.
Water softeners have a tank filled with resin beads that are coated with sodium ions. As hard water passes through the tank, the calcium and magnesium ions in the water are attracted to the resin beads and exchanged for sodium ions, resulting in softer water. The resin beads need to be periodically recharged or regenerated with a salt solution to replenish the sodium ions.