This schematic drawing give in handout 2-1-22. If the pharmaceutical manufacturer’s water supply is “hard” it needs to be “softened” by removal of calcium and magnesium salts.
Water is softened in a zeolite exchange column where the calcium and magnesium ions are exchanged for sodium. The sodium then has to be removed by de-ionization or reverse osmosis. When the zeolite reaches its exchange limit, it needs to be stripped of calcium and magnesium. This can be done using a brine solution, which exchanges sodium for calcium and magnesium, and the cycle starts again.
The inspectors should ensure that there is a proper procedure for the regeneration of the unit, and that the system is properly monitored and sanitized. The frequency of regeneration is something that the inspectors should ask the manufacturer to justify.