mho:

A mho is a measure of the ease along with that electric current will pass and is the inverse of an ohm,  a  measure  of  resistance  to  the  passage  of  electric  current. Conductance and conductivity are same qualities (conductivity is measured in µmhos/cm, so conductance must be converted to conductivity).  A µmhos is one millionth of a mho.  The whole conductivity of pure water could be calculated through adding the equivalent conductances of H and OH, multiplying through the normality, and then multiplying through 10^-3 l/cm³ and 10⁶ µmhos/mho.  For theoretically pure water that becomes the following.

 (350 + 192) (mhos cm²/ equivalent) × 10^-7 (equiv/ liter) × (10^-3 liters/ cm³⁾ × 10⁶ µmhos mho = .054 (µmho /cm)

A conductivity limit for demineralized water is 1 µmho/cm.