Boiling water with hot rocks.

[Irving]

Yeah but are they bad organisms? I assume they are.

Anyway, is ashy water safe to drink?

[Wulf202]

Depends on the ash. Coal? hell no. Wood ash yes in moderation, though it may cause digestion problems. If you're burning printed paper, I'd advise against it due to the funky stuff that can be produced from the inks but I have no real proof that it will harm.

Eating some charcoal from your (cooled) fire is a good way to stop the runs, FYI.