To do the ion replacement, the water in the house runs through a bed of small plastic beads or a chemical matrix called zeolite . The beads or zeolite are covered with sodium ions. As the water flows past the sodium ions, they swap places with the calcium and magnesium ions. Eventually the beads or zeolite contain nothing but calcium and magnesium and no sodium, and at this point they stop softening the water. It is now time to regenerate the beads or zeolite.
Regeneration involves soaking the beads or zeolite in a stream of sodium ions.
The strong brine displaces all of the calcium and magnesium that has built up in the zeolite and replaces it again with sodium. The remaining brine plus all of the calcium and magnesium is flushed out through a drain pipe. Regeneration can create a lot of salty water, by the way - something like 25 or so gallons. Inc. All rights reserved.