Take three fractions, the first being the "heads" or "tops" from the first condensed volume up to 5% of the original volume, the next being the "mains" from the

Take three fractions, the first being the "heads" or "tops" from the first condensed volume up to 5% of the original volume, the next being the "mains" from the next 90%, and the last being the "tails" or "bottoms" from the final 5%. Wash the packed column and boiling vessel with the heads and then discard them. Discard the tails. Repeat the process with the mains. Your twice-distilled mains are now pure water, discounting contamination from inferior distillation apparatus. Get some food-grade calcium chloride (E509, de-icing salt), magnesium sulfate (Epsom salt), sodium bicarbonate (baking soda), and potassium chloride (NoSalt brand table salt substitute) and add some (known) minerals back into the result for your drinking water, because pure distilled water has a very poor taste profile. The only types of chemical that cannot be easily removed by this distillation process are those that form azeotropes with water, such as ethanol, and those chemicals are unlikely to be present in quantities significant enough to be a problem.