This process reduces Bicarbonate and Carbonate Alkalinity and also the pH of the treated water.

A Purolite^® Strong Base Anion (SBA) resin is used and it is typically regenerated with salt - either Sodium or Potassium Chloride. This is very similar to the ion exchange process used in Water Softening, except here the Chloride ion of the salt is used. Purolite^® A300, known as a Type II SBA, is typically used. With the resin operating in the Chloride form, all of the Bicarbonate, Carbonate, Sulfate and Nitrate ions are taken up by the Purolite ion exchange resin and an equivalent amount of Chloride is released by the resin into the water.

If the hardness of the water to be treated is in excess of 1.7 mg/litre or 10 grains per gallon (gpg), then the water should generally be pre-softened.
The following Purolite resins (available in the Chloride (Cl^-) form) are typically used:

A300
A400
A600