Service Deionization is a convenient, safe and economical way to produce high-purity deionized water. It uses individual cartridges or tanks for the anion, cation, and mixed beds. When the individual cartridges are exhausted, the supplier replaces them with recharged units on site and the exhausted cartridges are removed to be regenerated at the supplier's premises. This arrangement eliminates the need to store chemicals. In addition, it saves water that does not have to be used for backwash.