FriendlyFinger - 25-7-2006 at 19:33
I have a water distiller with nickel plated elements. I charge it up with tap water filtered through a standard pre filter and carbon filter. pH is 7,
then after distilling the pH is about 5.5.
Also, the water leaves the condensor, approx 70 deg C, through a PE tube into a PE container which becomes charged. In fact I get a 20mm spark when I
go to touch the bung.
1) Why is the distilled water pH 5.5?
1) Why does it build up a charge?
[Edited on 26-7-2006 by FriendlyFinger]
Magpie - 25-7-2006 at 19:48
My guesses:
1) The water is absorbing CO2 from the air to give an acid pH.
2) Distilled water has very low conductivity. Perhaps it could be considered an insulator. Rubbing an insulator on PE generates a static charge.
[Edited on 26-7-2006 by Magpie]
simple - 25-7-2006 at 20:14
We have USA made vaccum destiler (capacity about 150 galon per hour), we also have normal boiling type distillers. Both give low pH reading when you
test it.
When we dig in to it we discovered that it is somthing to do with ionization??? of the water. Deionization statian is neded to bring distilled water
to pH 7.0
I had some documents on this somwhere..i will look and see if i can locate it...
The_Davster - 25-7-2006 at 20:29
Yeah, I noticed the same back in an introductory uni chem course, at the time to me distilled was the purest water available,so I was briefly confused
until I was informed about deionized. I initially thought it was equipment error, so I calibrated the pH meter a half dozen times.
What I find odd, is that it was neutral first, then after being distilled that it was acidic.
simple - 25-7-2006 at 21:13
Exacly! Suprases the hell out of you when you test and not familiar with the process. Water coming in is pH 7.1-7.4. After been passed thru softeners
and still plant you get 5.5-6.5! First think you do is blame the meter or seach for problem in the distiller 
In reality you simply do not know what you are doing
simple - 25-7-2006 at 21:24
Regarding static discharge - i would agree with Magpie
unionised - 25-7-2006 at 21:53
With sparks like that it's as well you weren't distilling moonshine. This variety of static has been responsible for some nasty accidents in the past.
Big solvent tanks now have grounding clips.
Any pure water (deionised or distilled or whatever) will get to about pH6.5 on exposure to air because of the CO2. It can't remember how it was
purified so that cannot make a difference.