Putting the desired counter-ion back on the ion exchanger, by displacing an ion of higher affinity with one of lower affinity. Regeneration alludes to the restoration of the spent resin ions in order the ion exchange process to work in softening the water. This process is done through the utilization of chemical regeneration solutions that use regenerate chemicals that are chosen because of several different factors. Regeneration usually restores up to 80% of the overall ion exchange resin with some of the hard ions remaining within the resin.