What can I do about the 74-year-old woman who pees on herself and will not change her clothes for months at a time?

Why would you stay with someone for six years (since 2019) who pees all over themselves and never showers?

There's nothing anyone here can do for you and I think you already know the answer to your problem.

Move out. Then call APS and report her as a vulnerable adult living alone because clearly that is what she is. Let them handle it.

As everyone has said, mentally ill or dementia. Call APS.

Yes, she is either mentally ill or has Dementia. Six years, though, with Dementia she should have worsened. I would not fool around with trying to get her to a doctor, I would call Adult Protection Services and have them take over her care. The State will become her gardian. APS maybe able to help you too with resources.

Call adult protective services on her behalf; you say there is nothing physically wrong with her, but if she is thus incontinent there absolutely IS something wrong. She is mentally suffering as well, whether with mental illness or with dementia, and needs care. If she has no concerned family please call Adult Protective Services in your area.

Why haven't you moved out yet? Surely the smell in the house and on this woman must be beyond disgusting. And most certainly it is very unsanitary.
You deserve better living conditions(in case you didn't already know that)even if it's in a homeless shelter, so please start packing your bags now and call Adult Protective Services(APS)on your way out the door to report a vulnerable adult living by themselves with either dementia or some kind of mental disorder, and they will come out and if need be take over her care.

This lady is either mentally ill or has a dementia. It’s not normal behavior and she should be medically evaluated. If you can persuade or even trick her into seeing a doctor, one you let know in advance about what you’re seeing, it would hopefully lead to a better idea of her condition and how to best get help for her. If this isn’t possible report the situation to Adult Protective Services in your county. It’s unfair and unhealthy to you both to continue as is

Yes, it's disgusting, and a sign that something is very wrong with her cognitively -- as in maybe dementia. Those of us on this forum who have or are dealing with LOs with dementia recognize this behavior as one that is very common with this disease. My Uncle did it. My best friend's Mom is doing it. The only solution is for this woman to go into a facility where she will get appropriate care. This is not something you can fix, so you will need to figure out what a solution is for you. I think 100% of the responders to your question are going to tell you to find another place to live because dementia is progressive and has no treatment or cure. If you stay there you will become her default caregiver and live out the stress of that thankless role as she becomes more and more impaired. Move out and report her to APS. Where does she poop? https://www.agingcare.com/articles/elderly-parents-who-wont-shower-or-change-clothes-133877.htm

My suggestion would be to move out, then call APS.