I use 3rd person almost all the time and havn't been able to fill my water bottles or canteens at several different locations. I've tried moving around to find the sweet spot, but it doesn't seem to work at all.

*edit - since this post I tried again. What I didn't realize is that I needed to put my water bottle/canteen onto my action bar and then have the item in my hands. At this point I was able to fill all containers without any issue.