I tried at home the method of distilling water by collecting the steam of the boiling water on a cloth placed over the top. You use sevelal cloths if possible one after the other and lift them off the pot with a stick to avoid being scalded. When they have cooled, you wring out the pure water in them.

I gave it a quick try by placing a handkerchief but the steam literally passed through it and the handkerchief never got wet enough. I also scalded one finger.

As Martin pointed out, some chemical substances could be distilled at the same time and it would take too much fuel anyway. It's certainly not possible if you are sitting on a roof, etc. The best is to store water.

Frankie