Typical residential water softer works on the principle of cation exchange or ion exchange. One of the biggest confusion about water softener is that they use salt to soften hard water. The truth is they use resin beads to soften and salt to clean resin beads. For more information how the technique works read this article from beginning to the end to under how a water softener work.
How a water softener work?
A water softener has two tanks resin tank and brine tank. The resin tank has polystyrene beads/ zeolite or resin beads and the mineral tank hold salt or sodium and liquid brine/ salt water. Polystyrene beads are negatively charged beads.
Hard water that is positively charged passes through the tank containing polystyrene beads. The positively charged molecules of hard are attracted to beads which are negatively charged and stick firmly to the beads, removing them in hard, therefore, providing soft water safe for drinking.
The softened water gets out of the resin tank and flows to your kitchen faucet ready for human consumption.
After a period resin beads are overcoated with minerals that they extract from hard water. The hard minerals coat makes the resin beads not operate properly resulting you clean them so that they can continue collecting hard minerals from your untreated water.
This is where the second tank comes in; it is filled with a brine solution (strong salt water). The brine solution flows through polystyrene beads rinsing hard minerals that have stick firmly on resin beads.
The brine solution and hard minerals are flushed out of the resin tank into a drain. The resin beads are cleaned and ready to attract and collect hard minerals present in your hard water. The process of when polystyrene beads need to be rinsed the minerals they have picked from hard water is called Regeneration
The process of rinsing resin beads can take two hours. During this time the water softening process stop unless you have a dual tank. Dual tank means the regeneration can take place on one tank while the other tank is softening hard water providing softened water throughout without interruption.
Water softeners replace the presence of the minerals in hard water with sodium using a process called ion exchange.
There are other alternatives that can help condition your hard water without the use of salt these are salt-free water softener and water conditioner each method use different techniques to treat hard water.