Water softeners work by a process know as ion exchange. The hard water passes through a high-quality cation exchange resin column inside a pressure vessel.

The resin removes the positively charged Calcium and Magnesium ions from solution and exchanges them for the ions of Sodium. When the resin becomes exhausted it is regenerated by drawing a solution of common salt called brine through the column. During regeneration, the hard metal ions are then released from the resin and replaced again with those of Sodium from the brine. The unwanted ions are flushed to drain along with the excess brine. Regeneration takes between 60 to 180 minutes depending on the size of the softener.
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