Is ion-exchange resin a precipitating water softener?
No. Ion-exchange resin is used in the water treatment tank of a standard water softener. This type of water softener works by replacing water hardness ions, Calcium and Magnesium Ions, with either Sodium or Potasium ions. The hardness ions are not precipitated, but instead are electrostatically attracted to surface of the resin beads where they replace less tightly bound Sodium or Potassium ions. These Sodium or Potasium ions enter the water stream and leave the water softener in the softened water. In a standard water softener, also known as an ion-exchange softener, no precipitation takes place in the water softening process. (Precipitation is the formation of solids from a solution.
