My daughter was actually placed in an apartment with TWO bathrooms. One bathroom has just a toilet, the other is a full bathroom, with a shower etc.
But anyway, the girls never even have to use the second bathroom. They're all on different schedules and it really just works out.
M says it's never been a problem, even when she's flaring. Even if she happens to be stuck at home in the bathroom, the other girls are out - in class, extracurriculars, jobs etc.
It's 5 girls and I was kind of worried about the bathroom situation (you know how much time girls can spend in the bathroom!!) but it really hasn't been an issue at all.
I would definitely remind your son about wanting privacy during a flare - think messy, loud diarrhea
.
I also wonder if you could have him talk to a college student with IBD -- maybe through your hospital or through CCFA? Also discuss it with his pediatric GI - the doc has most likely had other kids go to college and dealt with this issue before.