but I'm not following the difference between "Fresh" water and "Osmosis" water here.
  • Fresh water is what you get from the pipe - Conductance is between 50 and 1000 µS/cm (soft to hard water)
  • Osmosis water is what you get from a reverse osmosis filter - Conductance is lower that 10 µS/cm down to 0.0...1 µS/cm


The leakage sensor measures the conductance of air (if it´s dry) or the water (if there is a leakage). The conductance is the reciprocal of the resistance per cm.

If the water is too clean, it has very low conductance which means it has very hight resistance which also means it is an insulator like air. That´s the reason why a conductive probe can not recognize osmosis water.