I got in trouble for washing my delicates (read: lingerie) by hand in college, and they tried to impose a "students must use washing machines" rule. Though that probably had more to do with the fact that it was a conservative evangelical college and I guess they didn't want the reminder on display that their coeds had boobs?
That being said, one pair of pants? Ehhhhhhhh. I got away with three during college, and I still only have 4 (unless you count the scrubs, but those have to be washed with hot water.) but what do you do while those are washing/drying? Esp if they're jeans and they take 2+ days to dry?