1.1 ,This test method covers the determination of the operating characteristics of continuous electrodeionization (CEDI) devices, indicative of deionization performance when a device is applied to production of highly deionized water from the product water of a reverse osmosis system. This test method is a procedure applicable to feed waters containing carbonic acid or dissolved silica, or both, and other solutes, with a conductivity range of approximately 2 to 100 microsiemens-cm^-1.