I found a canteen yesterday and then i found a backpack. After a while i was feeling thristy so i looked over to my inventory to find out my water canteen was missing. I thought to myself that i had misplaced it when i found the backpack and carried on.

Today i found a canteen again and after logging off for some hours i came back and it was gone again so theres definitely something bugging here.

I filled the canteen 100% with water from a well at both times.