[EvaH (OP)]

Al wants to know:

A question of creating potable water with salt and a battery. I found online that a saturated salt solution of (distilled?) water can create sodium chlorite as a precipitate that can be filtered using standard coffee filters in a funnel. Both electrodes made of pencil lead (would it matter how pure the graphite lead is: HB, 2B, etc?) and a 9 volt, with voltage greater than 1.5 volts. Leave to stew for 16 hours minimum. Filter out the sodium chlorite to use as an antiseptic...?

What do you think?

Edit: Title changed from hydrolysing to electrolysing, as requested by bored chemist....

[Bored chemist]

It would generally be easier to carry water purifier tablets.

[alancalverd]

Sodium chloride is a reasonable emergency antiseptic - it kills most things that don't actually live in sea water and in sufficient concentration (like a saturated solution) it will cause pus to osmose across the epidermis.

If you must use pencil leads as electrodes, the hardness of the lead is immaterial. H grades just contain more inert clay binder than B grades.

Since sodium chlorite is almost as soluble in water as the chloride, it's difficult to see why it would precipitate out of the electrolyte solution. 

[Bored chemist]

the hardness of the lead is immaterial. H grades just...

The H and B in pencil grades stand for "hard" and "black"  respectively.

Incidentally, can someone change the thread title so it says "electrolysing" please?

[evan_au]

saturated salt solution of (distilled?) water

This is a bit of a contradiction...
- If it is a concentrated salt solution, it isn't distilled water (pure water), it is very impure water.
- If you had distilled (pure) water, it's not clear why you would need to purify it
- The most urgent need for people in emergency situations is to get drinking water, as lack of water will kill you faster than most infections. Salt water (and especially a saturated salt solution) is extremely bad to drink, as it makes your body more salty.

So just drink your pure water and make your way to a hospital.