Another idea I had, not sure if it would work but what if you took a bic lighter and heated the threads for a few seconds. I don't know if it would have any effect, but I was thinking localized high temps may kill on contact on the thread portion of a stainless steel bottle threads. Any thoughts of how much temperature it would take and time to kill localized on the threads. If in doubt, I just heat the whole bottle in a fire and boil the water.