I’m unsure how to write about bathrooms

I’m writing a dystopian steampunk literary YA novel (obvi) and I’m having trouble describing the bathroom in my MCs flying hotel. This is especially important for my story because approximately 75% of the action takes place in there (my MC has a problem with chronic constipation that is interfering with her participation in a hunger games-esque banana eating competition). What should I call the toilet? I don’t want to use modern terminology. Should I call it the shitter? The dump tank? The squattie? The steam bucket? The hole? I want something super evocative and period appropriate.

Thanks for your help!