I'm probably one of very few people in this thread that agrees w/ the OP that the dad is nuts.
I'm 23, and also live 'at home'. It's beneficial to me because I don't have to pay as much for rent here as I would if I moved out, and mom routinely indicates that she likes me being home, so that I can help pay bills, occasionally replace appliances for them (!), and help out on the farm if needed.
My dad used to throw a fit all the time about everyone taking long showers. I shower every morning, almost always 10 minutes exactly... if I feel like taking my time, maybe 15. I was getting ready for some event a few years ago, and dad decided to turn the water off while I was in the middle of a shower, and mom was getting ready in her bathroom... don't remember what she was doing. We were both livid. She pushed him out of the way and told him to stfu, and told me to go turn the water main back on. Later that night, she had a very short and to-the-point lecture for dad, telling him that if he ever did that again, she'd be happy to ship his belongings to any one of his siblings' houses, and he could move in with them. Then again, dad has never earned even 1/2 as much money as mom (and he wasn't terribly pleased when I earned more in my first job than he has ever made), and he showers once per week,
if he thinks he has to.