Conductivity of R/O water


I purchased a conductivity meter and of course already have measured everything that can be measured. There are 630 µS/cm in the tank. And I measure the R/O water to 60 µS/cm. Isn't that too much for R/O water? I heard of 20 µS/cm to be "normal".

60 µS/cm are indeed rather high for R/O water, this might indicate a mistake while measuring (e.g. miscalibration), dirty water containers or even a faulty R/O unit! A retaining rate of about 95 % can be assumed, it may even be up to 98 % in case of very goos (and accordingly maintained!) units.

As an average, values of about 20 µS/cm are realistic with R/O units. Very good units can even reach values below 10 µS/cm if the original water does not contain too much salts and the circumstances are ideal.

When assuming a linear relation between salinity and conductivity (which applies only roughly, the relation is not entirely linear in reality) you could expect measured values in the range of 30 µS/cm (in case of 95 % retaining rate) up to 12 µS/cm (in case of 98 % retaining rate) in the permeate, 600 µS/cm original conductivity provided.


Best regards

sera GmbH

Dr. Bodo Schnell


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