A bit further into the water purification thread linked:

Originally Posted By: Blast
Quote:
Just wondering... would there be any benefit to open, uncovered heating of the water so the vapors of those low-temp chemicals would leave the water first, then go to regular distillation. I'm talking if there was no other water to be had.


Yes. The other option is to discard the first 10% and last 15%of whatever is distilled over. Switch out the receiving container to collect only the middle portion of the fluid. Redistill the water a second time removing the same cuts if you are really concerned the water may be contaminated. You'll lose a fair amount of water but the water you do collect will be safe.

-Blast


Apparently it is not a time but rather a volume consideration. But don't take my word for it, I am by no means an expert. Blast on the other hand ... wink
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Uh ... does anyone have a match?