Kolchak ran from 1971-72. Very few people drank from plastic water bottles in the era.
” . . .Then found out it may have something to do with Hydrogen Sulphide Poisoning. . .”
Hydrogen sulphide flammable as well.
Could also consider Flakka. First remove clothing and act insane while naked, attack LEOs with the strength of ten, and then cannibalize faces of victims.
Seems demonic enough.