Janitors clean up mess and spills left behind from prisoners, construction work, foot traffic and blood after altercations. If these stains don't get cleaned up the prisoners' and staff's environment need will raise.
Janitors can be assisted by prisoners if a Cleaning Cupboard is constructed. The prisoners do the same job independently, but cannot clean inside of staff-only rooms. Also, janitors are able to help Laundry Service, where they will perform every part of the laundry.