I don't know why people are so amazed when I can change the big bottle in the water cooler at work.
I run into the same thing. Granted, we have people who are physically unable to change it (due to health issues), but mostly people just say it's too heavy. Our new director asked if the guy who came to replace the water changed it and I was like, 'uh, no, sometimes I've even done it.' He gave me a surprised look.