Hard water comes from the main water pipe into the softener.
Inside the softener resin tank there are thousands of tiny, plastic resin beads. As hard water passes through these beads, each bead attracts hardness minerals. This process is referred to as ion-exchanging. Water without the hardness minerals flows out of the softener and into the house as soft water. After a period of time, the resin beads need to be cleaned because they have been coated with hardness materials.