Electrodeionization is a new and modern technology (ionexes put into an electric field) for very low conductivity demiwater production. The electrodeionization process is applied as a terminal level of full demiwater cleaning produced by reverse osmosis. This produces a demiwater with conductivity of 10 - 15 MΩ/cm. It is a low-energy process, in which ionexchangers are continually regenerated in the electric field. This ensures a continual production of demineralized water of a constant quality, without the need of a chemical regeneration of the ionex resin.