Occurs when water passes through the mineral tank where positively-charged calcium and magnesium ions are exchanged with sodium onto the negatively-charged resin beads. The calcium and magnesium are retained on the media within the resin tank while the remainder of the water with sodium ions flows into the home, resulting in softened water. Eventually, all sodium ions are exchanged with the magnesium and calcium on the resin beads fill with calcium and magnesium and need to be regenerated.

The mineral tank is recharged with sodium from the brine tank solution and displaces calcium and magnesium, which is flushed down the drain during the backwashing phase.

At the end of the regeneration process, this stage is a final removal of the hardness ions and dirt that has accumulated in the mineral tank and flushes to the drain.

The mineral tank is rinsed with fresh water and loads the brine tank so that it is ready for the next softening cycle.

Recharging cycles are controlled by the electronic meter on the top of the tank. This can be set to recharge every specified number of days or as the electronic head recognizes that a certain amount of water has been used.