Strong Acid Cation (SAC) and Strong Base Anion (SBA) resin is housed in specially constructed vessels where it forms a bed, usually 0.9-1.5 meters deep. In some cases, it is supported by another bed of graded gravel or anthracite filter media. Water enters the top of the tank through a pipe, which distributes it over the surface of the exchanger bed. The treated water is drawn off by collector piping at the bottom.
The contaminant ions during ion exchange, replace the regenerant ions because they are preferred by the SAC and SBA resin. When no ions are left to take the place of the contaminant ions, the ion-exchange resin is regenerated with a suitable regenerant solution that saturates the resin bed with the appropriate ions.