One thing to keep in mind- if you think your ONLY water might be contaminated by petrochems, bring it to a boil without the lid. That will let the volatiles boil off.
Then cross your fingers and hope you don't die.
Good point on that. I was thinking along the lines of already having purified the water before it went in the nalgene and then pouring it into the cup for warming at a later time in my last post.