Annoying roommates help

So i have 3 other roommates and our ice machine isn’t the best. I love ice water so i went and bought an ice tray. Sometimes I’ll fill up the ice tray go to school and when I come home it’s just empty. Whoever is doing this doesn’t even ask & they could at least fill it then i wouldn’t care as much. I don’t really want my roommates using it but would that be selfish since our ice machine barely even makes ice?