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A chat on subreddit /r/NoStupidQuestions
human
Boiling kills most pathogens, possibly all of them (not qualified to answer to which extent). But that's  certainly the intent behind it.

Now simply boiling doesn't specifically "decontaminate" if you're talking about other dangerous substances in water.

To remove those, you would need to typically boil the water and recondense the steam so all the other impurity, toxins, chemicals etc. are getting seperated.
gpt
And that process of boiling and recondensing is what distillation is :)