water 既ionization問題~~~

不是完全不conduct electricity. 只是少而已.

Water conductivity

Pure water is not a good conductor of electricity. Ordinary distilled water in equilibrium with carbon dioxide of the air has a conductivity of about 10 x 10-6 W-1*m-1 (20 dS/m). Because the electrical current is transported by the ions in solution, the conductivity increases as the concentration of ions increases.
Thus conductivity increases as water dissolved ionic species.

Typical conductivity of waters:
Ultra pure water 5.5 · 10-6 S/m
Drinking water 0.005 – 0.05 S/m
Sea water 5 S/m