# Is pure water electrically conductive? [closed]

I know that water with some ions dissolved is a good conductor. I wonder whether it is true for pure water?

• This sort of question shows a severe lack of effort on the part of the poster. – Carl Witthoft Oct 10 '15 at 21:14
• Indeed, since DI water is characterized by its resistivity. Although DI water is not pure either... – Jon Custer Oct 10 '15 at 21:23
• I'm voting to close this question as off-topic because it shows insufficient prior research – John Rennie Oct 11 '15 at 11:05

No, pure water is not a good conductor at all, though the conductivity is not zero.

According to the LennTech webpage 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 $10 \times 10^{-6}\ W^{-1}m^{-1} \ (20 dS/m)$.

The reason is that there are no abundance of ions in pure water to conduct the electricity.

A table of comparisons is provided from the Physical Process Modelling website:

Note: the entry Water (distilled) is not the purest that water can be, see Ultrapure water which has significantly less conductivity than distilled water. But this table is given as a comparison with other materials.

• Is it good or bad compared to other materials? What about water in isolation from CO2? – Anixx Oct 10 '15 at 21:14
• lenntech.com/applications/ultrapure/conductivity/… gives a few things to compare with. $CO_2$ would increase the conductivity quickly because in water it converts to carbonic acid, which contributes ions and thus conductivity. – Gert Oct 10 '15 at 21:18
• @Anixx I have added a table with comparative information – user94040 Oct 10 '15 at 21:46

Even the purest water has some, very limited conductivity.

That's because water undergoes an auto-dissociation reaction:

$2H_2O(l) \rightarrow H_3O^+ (aq) + OH^- (aq)$.

The oxonium ($H_3O^+$) and hydroxide ($OH^-$) ions are charge carriers and allow limited current to be carried. But the total concentration of both ions together in ultra pure water is only about $2 \times 10^{-7}\:\mathrm{mol dm^{-3}}$, which is a very low value compared to ion concentrations in e.g. tap or river water.

• What is this conductivity compared to other materials? – Anixx Oct 10 '15 at 21:14
• lenntech.com/applications/ultrapure/conductivity/… gives a few things to compare with. $CO_2$ would increase the conductivity quickly because in water it converts to carbonic acid, which contributes ions and thus conductivity. – Gert Oct 10 '15 at 21:18