This process reduces the Bicarbonate Alkalinity and the pH of the treated water. A Purolite^®Weak Acid Cation (WAC) resin, typically regenerated with HCl or H₂SO₄, is used.

A Purolite Weak Acid Cation resin can also be used for both softening and dealkalizing of the water in order to reduce the ionic load to a downstream Purolite Strong Acid Cation (SAC) resin. This may also be accomplished by layering a Purolite WAC on a Purolite^® SAC resin bed in the same vessel, which can be economically regenerated by an upflow counter-current technique.

A Purolite WAC resin used for Dealkalisation only is typically regenerated with HCl or H₂SO₄. When used for high solids softening it must also be converted to the Sodium form with Na₂CO₃ or NaOH. In this event soft water must be used for the subsequent rinse.
CAUTION: These resins swell more than normal during exhaustion.

The PuroliteWAC resins of choice typically are:

C104

C104E
C106