How a Water Softener Works
Hard water is softened by removing the calcium and magnesium it contains. When hard water passes through the softening system's resin bed, the calcium and magnesium (hardness) ions are removed through an ion exchange process, so only softened water passes through to your home. Once the resin bed fills up with hardness ions, it must be regenerated (cleaned). Salt is typically used in the regeneration process and restores the resin to a "clean" state so the ion exchange process can begin again.
Hard Water can easily be treated before it damages fixtures and appliances in your home
Softening: A water softener works on the principle of an ion exchange in which ions of the hardness minerals are exchanged for sodium , effectively reducing the concentration of hardness minerals to tolerable levels. The most common way to condition and treat household water (I'm clearly not saying the best...)is with an ion exchange water softener. This unit uses sodium chloride (table salt) to recharge beads made of ion exchange resin that exchange hardness mineral ions for sodium ions. Artificial or natural zeolites can also be used. As the water passes through and around the beads, the hardness mineral ions are preferentially absorbed, displacing the sodium ions. This process is called ion exchange. When the bead or sodium zeolite has a low concentration of sodium ions left, it is exhausted, and can no longer soften water. The resin is recharged by flushing (often back-flushing) with saltwater. The high excess concentration of sodium ions alter the equilibrium between the ions in solution and the ions held on the surface of the resin, resulting in replacement of the hardness mineral ions on the resin or zeolite with sodium ions. The resulting saltwater and mineral ion solution is then rinsed away, and the resin is ready to start the process all over again. This cycle can be repeated many times. One problem here is that water softeners are being banned in some large city's because of the pollution they create, and more are expected to follow suite.