Why does my elderly parent refuse to wash his hands after going to the bathroom?

It's not normal but it IS a common complaint from families living with dementia. I'm curious how you know whether or not he is washing, is someone supervising him there? Try handing him a warm, soapy washcloth or a disposable wipe when he comes out the door.

My mother had this problem too and it grossed me out.

When I was there helping her I would make sure she stood in front of the sink (using this as a support so no excuses) and ask her to wash her hands. I would guide her hands under running water then squirt soap in her palms. She would get the message.

Later in the NH,the same thing.

But when you can’t watch them use Purel or some other alcohol based hand sanitizer. Make sure they use it whenever they enter the room you are in.

This was a huge struggle for me too.

I think it is a generational thing. Washing hands probably was not pushed when they went to school back in the 30s. I had to make a big deal of it everytime my father used the bathroom. And I would send him back to do it if he 'forgot'.

What about putting sanitizer in the bathroom?

We've all seen people in public restrooms who exit the stall and make a beeline for the door without stopping to wash, he could have always been one of those people. Sanitizer is no replacement for soap and water (especially after a bowel movement).
And if it is happening because they are reverting to habits from the days of the outhouse then there some serious cognitive deficits and it's time for supervision in this and probably many other aspects of their life.