Water and where it
Years ago, when I dabbled with some chemical engineering stuff, which included water treatment, I did recall seeing a classification of water and there were 7 levels (if I recall correctly). Tap water was about 3. Distilled was about 5 and stuff you put in nuclear reactors, etc was about 7.
We use a system in labs with numbers the other way around (possibly the same system?) its an ASTM grading system.
Tap water is type 3 I think
Type 2 is general lab use for things like media prep and is anything above 1.0 MO-cm although we usually run in the 14-16 range. Usually the glasswashers are fed with this for the rinse stage as it leaves no water marks.
Type 1 is 18 MO-cm produced by further polishing type 2, we use it for HPLC stuff.
Type 1+ is 18.2 MO-cm, I'm not a chemist but I believe its more or less impossible to get water any purer than that.
A while back we produced analysers to check for heavy metals in waste water and we ran a ring main through the building at 18.2, although out of the taps it was sometimes a little below 18.
I imagine most water out of mines would drop off the end of the scale :lol: