Basically, the resin or mineral inside the mineral tank is specially designed to remove “hard” particles of lime and calcium, by a simple ion exchange process. The resin beads inside the softener tank have a different or opposite electrical charge than the dissolved particles of the incoming water. Because of this electrical charge difference, the dissolved particles suspended in your water will cling to the resin beads on contact, thereby ridding the water of these particles, causing the water exiting the unit to be “soft”. The resin has a limit to how much of these hardness particles it can hold, which is why there are many different sizes of softeners and also why regeneration or brining is required.