If I boil water at home, when and how do I know I've boiled the water long enough to make distilled water?

Answer 1

You can't make distilled water that way. Boiled water can be made safe to drink from germs by boiling (that is boiling will kill germs but it won't detoxify from metals or many other poisonous materials nor will it remove most other minerals). Boiling water CAN make temporarily hard water soft(er) by make the bicarbonates precipitate as the carbonate, but even then it must be filtered to removed the precipitate. That still leaves the other minerals in the water, including any poisonous materials.