Demineralised water

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Demineralized water , also known as deionized water , fully demineralized water ( VE water ) or deionized water , is water (H 2 O) without the salts found in normal spring and tap water , which are dissolved as anions and cations . It is mainly used in technical applications as an operating material (for example as a heat transfer medium in the coolant circuit of a power plant ), but is also used in chemistry and biology as a solvent and sometimes also as a cleaning agent. Certain processes or applications require so-called ultrapure water , where certain and high specifications for the purity must be met.

Demineralized water is obtained from drinking water through ion exchange . Another method is the extraction from service water by upstream reverse osmosis with downstream residual desalination via a mixed bed filter . Tap water is used as raw water for smaller quantities and surface or well water for larger quantities for industrial needs. If it has also been sterilized , it is sold as distillate-like water .

To determine the degree of purity of demineralized water, the electrical conductivity is measured with conductivity meters. The conductivity is given in S / m (Siemens per meter). Since demineralized water has a very low conductivity, the common unit is mS / m and, in the technical field, µS / cm.

See also


  • Leonhard A. Hütter: Water and water analysis. 6th edition. Salle + Sauerländer, Frankfurt 1994, ISBN 3-7941-3270-X .

Individual evidence

  1. G. Kuhnle: Complete desalination system with reverse osmosis . In: VGB Kraftwerkstechnik 74 , 1994, issue 10, pp. 875-878.