Contaminating a canteen by filling it with untreated water

From BearWiki

In the Everglades episode, Bear demonstrates filling his canteen by straining the “big stuff” out with his shirt.[1] He made a serious blunder by not straining the water into his cup first and then boiling it before adding it to his canteen. His canteen is now contaminated so that he can’t trust taking another drink from it directly. While he was stopped and had a fire going, he should have taken the time to boil all the water he needed to drink and fill his canteen at the same time. He now will need to stop, build a fire and boil water every time he needs to take drink.

[edit] Analysis

Oppose: Wouldn't pouring freshly boiled water into the canteen kill any bacteria inside it at a later time anyways?

Support: Only if you boiled the whole canteen's worth.