Most water softeners work by adding salt to water as it enters your home. When hard water with minerals comes in contact with resin beads attached to sodium/potassium ions, an ion exchange trades salt for minerals. Generally a water softener system will include a salt storage tank connected to an ion exchange resin tank, which is then connected to your water heater and your plumbing lines. Water comes in, minerals are removed in the ion exchange tank with salt from the storage tank, and soft water is transferred to the water heater and to your home.