Abstract: A water purification system and method for the use and maintenance service of said system, whereby a combination of a primary ion exchange resin element, a secondary ion exchange resin element, a water quality monitor placed so as to indicate that the primary resin element is exhausted and the secondary resin element is being used, activated carbon elements, sterilizing or sanitizing filters, and sanitizing components such as UV radiation, or other sanitizing technologies, is used to produce purified water for consumption or other intended use. Both the primary and secondary ion exchange resin elements are comprised of one or more mixed bed ion exchange resin unit(s), or one or more paired set(s) of anion and cation exchange resin units arranged in series. The system's redundant ion exchange resin configuration allows purification to continue after the resin in the primary resin element is exhausted and can no longer remove unwanted impurities in the water.