What do I do if my Dad, with dementia, won't take a bath?

They should handle this at the facility. If it is a nursing home, have the MD order weekly bathing. If it is assisted living, they really can't do anything if he refuses, but they might ask him to move out if he stinks.

You can also hire outside person or CNA to come in and bath him. If you do a weekly visit, try to tell him you will bring a treat if he showers. He may need someone to be in the room with him giving him privacy, however cueing him on what to do...for example, remove your shirt, pj bottoms, underwear...now step in shower, now here is washcloth with gel on it pop...now wash your face..good dad, now wash your arm, good, now your chest, god job, now legs....put shampoo in his hand, then lift his hand to his head and start his hand motion to wash his hair. These prompts can trigger him to bathe himself. Then have warm blanket or beach towel ready to stave off the chill. Then reward with a nice treat, special carry out lunch that you bring over or whatever.